An Updated Classification of Retinal Detachment With Proliferative Vitreoretinopathy Robert Machemer, M.D., Thomas M. Aaberg, M.D., H. MacKenzie Freeman, M.D., Alexander R. Irvine, M.D., John S. Lean, M.D., and Ronald M. Michels, M.D.t
The Retina Society classification on proliferative vitreoretinopathy of 1983 has been updated to accommodate major progress in understanding of this disease. There are three grades describing increasing severity of the disease. Posterior and anterior location of the proliferations have been emphasized. A more detailed description of posterior and anterior contractions has been made possible by adding contraction types such as focal, diffuse, subretinal, circumferential contraction, and anterior displacement. The extent of the abnormality has been detailed by using clock hours instead of quadrants.
longed intraocular gas tamponade, carried out at multiple centers, led investigators in that study to reclassify proliferative vitreoretinopathy." Modifications were also proposed by other investigators} In response, the Retina Society appointed a committee to reevaluate the classification of proliferative vitreoretinopathy and suggest modifications if needed. The Committee was charged with finding a uniform, internationally acceptable classification to eliminate possible confusion resulting from multiple new classification attempts in the United States and elsewhere. This new uniform classification is now complete.
As
PROLIFERATIVE VITREORETINOPATHY became amenable to therapy, need for a more detailed description of the various stages of the disease arose.' To meet the need, in 1983 the Retina Society proposed an internationally accepted classification." More recently, however, major progress in the understanding of the disease and therapeutic advancements have revealed shortcomings in this classification. In 1989, results of a major randomized trial to evaluate the efficacy of silicone oil compared to pro-
Accepted for publication May 1, 1991. From the Department of Ophthalmology, Duke University, Durham, North Carolina (Dr. Machemer); Department of Ophthalmology, Emory University, Atlanta, Georgia (Dr. Aaberg); Retina Associates, Inc., Boston, Massachusetts (Dr. Freeman); Department of Ophthalmology, University of California, San Francisco, California (Dr. Irvine); Department of Ophthalmology, University of Southern California, Los Angeles, California (Dr. Lean); and Retina Center at Saint Joseph Hospital, Baltimore, Maryland (Dr. Michels). This study was sponsored by the Retina Society and supported by Research to Prevent Blindness Inc., New York, New York, and the Helena Rubinstein Foundation, New York, New York. tDied Jan. 15, 1991. Reprint requests to Robert Machamer, M.D., Box 3802, Duke University Eye Center, Durham, NC 27710.
©AMERICAN JOURNAL OF OPHTHALMOLOGY
112:159-165,
Classification The Retina Society classification of 1983 described proliferative vitreoretinopathy in four grades of severity: A, B, C, and D. The new classification retains Grades A and B, modifies Grade C, and eliminates Grade D.
Grade A--Denotes the earliest recognizable manifestation of intraocular proliferation, that is, pigment clumps resulting from multiplication of pigmented cells in the vitreous matrix. Clusters of pigmented cells may also be seen on the surface of the inferior retina. A Tyndall effect appears as the result of exudation into the vitreous cavity. The posterior vitreous surface is less mobile and better visible (Fig. 1). Grade B--Defined by the presence of wrinkling of the inner retinal surface and retinal breaks with rolled or irregular edges (Fig. 2). The retina may appear rigid, and the retinal vessels may show tortuosity brought about by very thin preretinal membranes that are not visible by indirect ophthalmoscopy. Decreased mobility of the vitreous is also observed. AUGUST,
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Fig. 1 (Machemer and associates). Proliferative vitreoretinopathy Grade A. Schematic drawing of pigmented clumps and Tyndall effect visible in vitreous with the slit lamp. The posterior vitreous surface appears condensed. (Published courtesy of Ophthalmology 90:121, 1983.)
Grade C--Defined by full-thickness rigid retinal folds. Grade C proliferative vitreoretinopathy is subdivided into posterior (P) and anterior (A) forms, the dividing line between the two areas being roughly the equator of the globe. The extent of the proliferation in each area is expressed by the number of clock hours of the retina involved (1-12). Frequently the proliferations are not contiguous. The vitreous is heavily condensed and contains strands.
retinopathy. The Committee perceived, however, that a more detailed description of the findings was necessary. Thus Grade C is subdivided to describe the following types of contraction (Table 2). The extent of the proliferation of each type may also be expressed in the number of retinal clock hours involved.
These revised grades (Table 1) give a comprehensive general picture of proliferative vitreo-
Type I--Focal posterior contraction denotes a single starfold or multiple isolated single starfolds. Localized contraction in the center of the starfold causes radiating full-thickness retinal folds in a star-shaped pattern (Fig. 3). This type occurs posterior to the vitreous base.
Fig. 2 (Machemer and associates). Proliferative vitreoretinopathy Grade B. Irregular and partially rolled edge of retinal tear.
Fig. 3 (Machemer and associates). Proliferative vitreoretinopathy Grade C. Type I, focal contraction (starfold).
Type 2--Diffuse posterior contraction is the result of the confluence of many focal epicenters of contraction, marked by areas of irregular full-thickness retinal folding (Fig. 4). This type also occurs posterior to the vitreous base. Type 3--Subretinal proliferations caused by
solid strands can appear as an annular fold of the retina in the region near the optic disk, as a subretinal linear band with retina draped over it, similar to a clothesline, or when caused by membranes as irregular sheets with a motheaten appearance (Fig. 5). They are often pigmented but may also lack pigment. Only if the subretinal proliferations elevate the retina or produce fixed retinal folds, which are evident by ophthalmoscopy, the extent of the proliferation is recorded. The extent of flat subretinal sheets, which are often difficult to visualize, is not recorded. Subretinal proliferations are found both posteriorly and anteriorly to the equator.
Type 4--Circumferential contraction is the result of diffuse membrane contraction on the retinal surface and along the juncture of the retina and the posterior surface of the detached vitreous. This is usually anterior to the equator. Contraction of preretinal tissue and across the posterior hyaloid surface produces central displacement of the retina, with stretching of the retina anterior to it as well as radial folds and a funnel formation of the retina posterior to it. Circumferential contraction can also occur after TABLE 1 PROLIFERATIVE VITREORETINOPATHY DESCRIBED BY GRADE GRADE
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FEATURES
A
Vitreous haze; vitreous pigment clumps; pigment clusters on inferior retina
B
Wrinkling of inner retinal surface; retinal stiffness; vessel tortuosity; rolled and irregular edge of retinal break; decreased mobility of vitreous
C P 1-12
Posterior to equator: focal, diffuse, or circumferential full-thickness folds'; subretinal strands'
C A 1-12
Anterior to equator: focal, diffuse, or circumferential full-thickness folds'; subretinal strands'; anterior displacement'; condensed vitreous with strands
'Expressed in the number of clock hours involved.
TABLE 2 GRADE C PROLIFERATIVE VITREORETINOPATHY DESCRIBED BY CONTRACTION TYPE
TYPE
LOCATION (IN RELATION TO EQUATOR)
FEATURES
1. Focal
Posterior
Starfold posterior to vitreous base
2. Diffuse
Posterior
Confluent starfolds posterior to vitreous base. Optic disk may not be visible
3. Subretinal
PosteriorI anterior
Proliferations under the retina: Annular strand near disk; linear strands; motheaten-appearing sheets
4. Circumferential Anterior
Contraction along posterior edge of vitreous base with central displacement of the retina; peripheral retina stretched; posterior retina in radial folds
5. Anterior displacement
Vitreous base pulled anteriorly by proliferative tissue; peripheral retinal trough; ciliary processes may be stretched, may be covered by membrane; iris may be retracted
Anterior
vitrectomy and produce similar central displacement of the retina (Figs. 6 and 7).
Type 5--Anterior displacement of the vitre-
ous base usually occurs in eyes that have previously undergone vitreous surgery especially after use of an intraocular gas or oil tamponade or after trauma. It may also occur, however, in some cases of long-standing untreated proliferative vitreoretinopathy. Proliferative tissue of varying density infiltrates the vitreous base or is present on the surface of remnants of the vitreous base. This tissue extends anteriorly and attaches to the pars plicata of the ciliary body, posterior surface of the iris, or even the pupillary margin.! Traction is exerted in two directions: posteroanterior and circumferential. Because the anterior vitreous base is anchored to the pars plana, the posterior vitreous base, the peripheral retina, and even some pars plana epithelium are pulled both forward and inward, creating a circumferential fold of the retina. A trough of varying width and depth appears anterior to this circumferential fold (Fig. 8). In some eyes, the trough may appear to be closed if the peripheral retina is dragged
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Fig. 4 (Machemer and associates). Proliferative vitreoretinopathy Grade C. Type 2, diffuse contraction with multiple confluent retinal folds.
anteriorly and becomes adherent to the anterior structures, with resulting posterior retraction of the iris.
Method of Grading
Grading takes place by means of a standardized method depicting each type of contraction On a retinal diagram (Fig. 9). The posterior
August, 1991
types of contraction and their location are recorded in the postequatorial portion of the diagram: Type 1, focal contraction (starfold), is depicted by a large X centered On the starfold. Type 2, diffuse contraction, is shown by a group of large Xs. Subretinal proliferation can occur in both the postequatorial and preequatorial parts of the diagram: Type 3, subretinal proliferation, is indicated by a broken black line. The anterior forms of contraction and their location are recorded in the preequatorial portion of the diagram: Type 4, circumferential contraction, is shown by a series of small xs. Type 5, anterior displacement, is depicted like circumferential contraction with arrows pointing anteriorly. Using a retinal diagram, One can quickly determine the grade and type of proliferative vitreoretinopathy. The grading is illustrated in Figure 9. The total numbers of clock hours of traction in the posterior (postequatorial) and the anterior (preequatorial) portion of the diagram are noted separately. The overall extent of proliferative vitreoretinopathy denotes the number of clock hours of involvement by traction affecting the posterior (CP) and anterior (CA) parts of the retina (for example, CP-6, CA-9).
Fig. 5 (Machemer and associates). Proliferative vitreoretinopathy Grade C. Type 3. Left, Subretinal contraction causing a semi-annular fold of the retina on nasal side of optic nerve head while ill-defined motheaten sheets fold its temporal aspect. Right, A high retinal fold is created by partially pigmented subretinal band with retina draped over it.
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Fig. 6 (Machemer and associates). Proliferative vitreoretinopathy Grade C. Type 4, circumferential contraction with proliferation immediately behind insertion of the posterior hyaloid pulling retina centrally, stretching the retina anterior to it and creating radial folds posteriorly. Schematic drawing of situation in nonvitrectomized eye (left) and vitrectomized eye (right). Arrows show direction of pull. A more detailed description of the proliferative vitreoretinopathy can be provided by adding the type of contraction to the grade. For example, the classification CP-6, type I, 2, 3 describes visible postequatorial proliferations (focal, diffuse, subretinal) covering a total of six clock hours. The classification CA-9, type 4, 5 describes preequatorial circumferential proliferations and anterior displacement covering nine clock hours. Because the fovea is the center of the diagram, expressing the extent of the fold in this area in clock hours is difficult. A focal contraction in the macula is judged to represent one clock hour. A diffuse macular contraction covering a larger area is evaluated as if it were slightly shifted to the temporal side. An optional, even more detailed description can be achieved by adding to each type the number of clock hours involved, similar to those in the grades. Also, proliferations of various types can overlap. Expansion of the example CP-6, type I, 2, 3 would be represented as CP-6 type I-I, 2-2, 3-4. In this case the different types all occur within the total extent of the six clock hours. Grade C anterior vitreoretinopathy-9, type 4, 5 would appear as CA-9, type 4-8, 5-3.
Discussion The proposed classification summarized in Tables 1 and 2 has been developed to retain as much as possible of the old classification" and by drawing on the experience of the Silicone Study group and others.v' The major changes in the grading system from the original 1983 Retina Society classification are the distinction between posterior and anterior abnormalities, addition of a description of contraction types, abandoning the description of the configuration of the retinal funnel, while using clock hours instead of quadrants to describe the extent of the abnormality. Although the ophthalmoscopic picture of proliferation effects in the postequatorial portions of the eye was reasonably well described under the old system, preequatorial findings were neglected, especially in eyes that had previously undergone vitrectomy. For this reason Grade C has now been subdivided into posterior and anterior regions in order to allow for a description of the clinical picture and types of contraction in anterior proliferative
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Fig. 7 (Machemer and associates). Proliferative vitreoretinopathy Grade C. Type 4, circumferential contraction. vitreoretinopathy'f (Table 1). More detailed descriptions of the posterior proliferation effect are made possible by adding the contraction types (focal, diffuse, and subretinal contractions). Anterior proliferation effects are more fully described by addition of references to circumferential contraction':" and anterior dis-
August, 1991
placement (Table 2). Because experience has shown little correlation between funnel size and severity or prognosis, Grade D of the previous classification was abandoned. Under the old system, although subretinal proliferations were known as part of the clinical picture, I no consideration was given to their presence.! They have now been included as contraction type 3. Under the revised system, however, still no attempt is made to detail information on these strands, as they are often difficult to define. The Committee chose not to record information regarding the number, size, and location of retinal breaks in this new classification. Their conclusion was that doing so would only complicate the classification. Furthermore, many retinal holes are hidden or purposefully or inadvertently created during surgery, thereby rendering this information of little value. Individual researchers may, of course, opt to include such information in their own case reports. No effort was made to define the level of activity of the proliferative process because present knowledge is insufficient to provide objective measures.
Fig. 8 (Machemer and associates). Proliferative vitreoretinopathy Grade C. Type 5, anterior displacement of the vitreous base. Left, Schematic drawing shows how peripheral retina is pulled forward by fibrous adhesions between vitreous base, ciliary body, and iris to form a retinal trough in a previously vitrectomized and buckled eye. (Courtesy of Springer Verlag, 1988; Freeman and Tolentino, Proliferative Vitreoretinopathy, p. 25, Fig. 5.) Right, The most extreme fundus periphery with fibrous tissue in the pars plana area (arrow) causing radial folds (x) in detached retina overlying a circumferential buckle.
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Fig. 9 (Machemer and associates). Retinal diagram to depict the various types of fullthickness retinal folding.
Type 1: focal = X Type 2: diffuse = X X X Type 3: subretinal = - Type 4: circumferential
=
XXX)(
Type 5: anterior displacement
t t =xxxx
In an effort to promote generalized use of this new classification, the Committee has tried to keep it as simple as possible. The committee approach in formulating a classification is advantageous in that a common denominator must be found for differing individual opinions. A classification is best built on ophthalmoscopic and biomicroscopic observations rather than on interpretation of the visible findings. The Committee presents this new classification in the full awareness that it only represents present knowledge and may well need future revisions.
References 1. Machemer, R.: Pathogenesis and classification of massive periretinal proliferation. Br. ]. Ophthalmol. 82:737, 1978. 2. The Retina Society Terminology Committee: The classification of retinal detachment with prolif-
erative vitreoretinopathy. Ophthalmology 90:121, 1983. 3. Lean, ]. S., Stern, W. A., Irvine, A. R., Azen, S. P., and The Silicone Study Group: Classification of proliferative vitreoretinopathy used in the Silicone Study. Ophthalmology 96:765, 1989. 4. Heimann, K., and Wiedemann, P.: Cologne classification of proliferative vitreoretinopathy. In Heimann, K., and Wiedemann, P. (eds.): Proliferative Vitreoretinopathy. Heidelberg, Kaden Verlag, 1989, pp. 148 and 149. 5. Freeman, H. M., Elner, S. G., Tolentino, F. I., Schepens, C. L., Elner, V. N., and Albert, D. M.: Anterior PVR. Part I. Clinical findings and management. In Freeman, H. M., and Tolentino, F. I. (eds.): Proliferative vitreoretinopathy. New York, Springer Verlag, 1988, pp. 22-33. 6. Lewis, H., and Aaberg, T. M.: Anterior proliferative vitreoretinopathy. Am. ]. Ophthalmol. 105:277, 1988. 7. Elner, S. G., Elner, V. M., Diaz-Rohena, R., Freeman, H. M., Tolentino, F. I., and Albert, D. M.: Anterior proliferative vitreoretinopathy. Clinicopathologic, light microscopic and ultrastructural findings. Ophthalmology 95:1349, 1988.
The Retina Society classification on proliferative vitreoretinopathy of 1983 has been updated to accommodate major progress in understanding of this disease. There are three grades describing increasing severity of the disease. Posterior and anterior location of the proliferations have been emphasized. A more detailed description of posterior and anterior contractions has been made possible by adding contraction types such as focal, diffuse, subretinal, circumferential contraction, and anterior displacement. The extent of the abnormality has been detailed by using clock hours instead of quadrants.
longed intraocular gas tamponade, carried out at multiple centers, led investigators in that study to reclassify proliferative vitreoretinopathy." Modifications were also proposed by other investigators} In response, the Retina Society appointed a committee to reevaluate the classification of proliferative vitreoretinopathy and suggest modifications if needed. The Committee was charged with finding a uniform, internationally acceptable classification to eliminate possible confusion resulting from multiple new classification attempts in the United States and elsewhere. This new uniform classification is now complete.
As
PROLIFERATIVE VITREORETINOPATHY became amenable to therapy, need for a more detailed description of the various stages of the disease arose.' To meet the need, in 1983 the Retina Society proposed an internationally accepted classification." More recently, however, major progress in the understanding of the disease and therapeutic advancements have revealed shortcomings in this classification. In 1989, results of a major randomized trial to evaluate the efficacy of silicone oil compared to pro-
Accepted for publication May 1, 1991. From the Department of Ophthalmology, Duke University, Durham, North Carolina (Dr. Machemer); Department of Ophthalmology, Emory University, Atlanta, Georgia (Dr. Aaberg); Retina Associates, Inc., Boston, Massachusetts (Dr. Freeman); Department of Ophthalmology, University of California, San Francisco, California (Dr. Irvine); Department of Ophthalmology, University of Southern California, Los Angeles, California (Dr. Lean); and Retina Center at Saint Joseph Hospital, Baltimore, Maryland (Dr. Michels). This study was sponsored by the Retina Society and supported by Research to Prevent Blindness Inc., New York, New York, and the Helena Rubinstein Foundation, New York, New York. tDied Jan. 15, 1991. Reprint requests to Robert Machamer, M.D., Box 3802, Duke University Eye Center, Durham, NC 27710.
©AMERICAN JOURNAL OF OPHTHALMOLOGY
112:159-165,
Classification The Retina Society classification of 1983 described proliferative vitreoretinopathy in four grades of severity: A, B, C, and D. The new classification retains Grades A and B, modifies Grade C, and eliminates Grade D.
Grade A--Denotes the earliest recognizable manifestation of intraocular proliferation, that is, pigment clumps resulting from multiplication of pigmented cells in the vitreous matrix. Clusters of pigmented cells may also be seen on the surface of the inferior retina. A Tyndall effect appears as the result of exudation into the vitreous cavity. The posterior vitreous surface is less mobile and better visible (Fig. 1). Grade B--Defined by the presence of wrinkling of the inner retinal surface and retinal breaks with rolled or irregular edges (Fig. 2). The retina may appear rigid, and the retinal vessels may show tortuosity brought about by very thin preretinal membranes that are not visible by indirect ophthalmoscopy. Decreased mobility of the vitreous is also observed. AUGUST,
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Fig. 1 (Machemer and associates). Proliferative vitreoretinopathy Grade A. Schematic drawing of pigmented clumps and Tyndall effect visible in vitreous with the slit lamp. The posterior vitreous surface appears condensed. (Published courtesy of Ophthalmology 90:121, 1983.)
Grade C--Defined by full-thickness rigid retinal folds. Grade C proliferative vitreoretinopathy is subdivided into posterior (P) and anterior (A) forms, the dividing line between the two areas being roughly the equator of the globe. The extent of the proliferation in each area is expressed by the number of clock hours of the retina involved (1-12). Frequently the proliferations are not contiguous. The vitreous is heavily condensed and contains strands.
retinopathy. The Committee perceived, however, that a more detailed description of the findings was necessary. Thus Grade C is subdivided to describe the following types of contraction (Table 2). The extent of the proliferation of each type may also be expressed in the number of retinal clock hours involved.
These revised grades (Table 1) give a comprehensive general picture of proliferative vitreo-
Type I--Focal posterior contraction denotes a single starfold or multiple isolated single starfolds. Localized contraction in the center of the starfold causes radiating full-thickness retinal folds in a star-shaped pattern (Fig. 3). This type occurs posterior to the vitreous base.
Fig. 2 (Machemer and associates). Proliferative vitreoretinopathy Grade B. Irregular and partially rolled edge of retinal tear.
Fig. 3 (Machemer and associates). Proliferative vitreoretinopathy Grade C. Type I, focal contraction (starfold).
Type 2--Diffuse posterior contraction is the result of the confluence of many focal epicenters of contraction, marked by areas of irregular full-thickness retinal folding (Fig. 4). This type also occurs posterior to the vitreous base. Type 3--Subretinal proliferations caused by
solid strands can appear as an annular fold of the retina in the region near the optic disk, as a subretinal linear band with retina draped over it, similar to a clothesline, or when caused by membranes as irregular sheets with a motheaten appearance (Fig. 5). They are often pigmented but may also lack pigment. Only if the subretinal proliferations elevate the retina or produce fixed retinal folds, which are evident by ophthalmoscopy, the extent of the proliferation is recorded. The extent of flat subretinal sheets, which are often difficult to visualize, is not recorded. Subretinal proliferations are found both posteriorly and anteriorly to the equator.
Type 4--Circumferential contraction is the result of diffuse membrane contraction on the retinal surface and along the juncture of the retina and the posterior surface of the detached vitreous. This is usually anterior to the equator. Contraction of preretinal tissue and across the posterior hyaloid surface produces central displacement of the retina, with stretching of the retina anterior to it as well as radial folds and a funnel formation of the retina posterior to it. Circumferential contraction can also occur after TABLE 1 PROLIFERATIVE VITREORETINOPATHY DESCRIBED BY GRADE GRADE
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FEATURES
A
Vitreous haze; vitreous pigment clumps; pigment clusters on inferior retina
B
Wrinkling of inner retinal surface; retinal stiffness; vessel tortuosity; rolled and irregular edge of retinal break; decreased mobility of vitreous
C P 1-12
Posterior to equator: focal, diffuse, or circumferential full-thickness folds'; subretinal strands'
C A 1-12
Anterior to equator: focal, diffuse, or circumferential full-thickness folds'; subretinal strands'; anterior displacement'; condensed vitreous with strands
'Expressed in the number of clock hours involved.
TABLE 2 GRADE C PROLIFERATIVE VITREORETINOPATHY DESCRIBED BY CONTRACTION TYPE
TYPE
LOCATION (IN RELATION TO EQUATOR)
FEATURES
1. Focal
Posterior
Starfold posterior to vitreous base
2. Diffuse
Posterior
Confluent starfolds posterior to vitreous base. Optic disk may not be visible
3. Subretinal
PosteriorI anterior
Proliferations under the retina: Annular strand near disk; linear strands; motheaten-appearing sheets
4. Circumferential Anterior
Contraction along posterior edge of vitreous base with central displacement of the retina; peripheral retina stretched; posterior retina in radial folds
5. Anterior displacement
Vitreous base pulled anteriorly by proliferative tissue; peripheral retinal trough; ciliary processes may be stretched, may be covered by membrane; iris may be retracted
Anterior
vitrectomy and produce similar central displacement of the retina (Figs. 6 and 7).
Type 5--Anterior displacement of the vitre-
ous base usually occurs in eyes that have previously undergone vitreous surgery especially after use of an intraocular gas or oil tamponade or after trauma. It may also occur, however, in some cases of long-standing untreated proliferative vitreoretinopathy. Proliferative tissue of varying density infiltrates the vitreous base or is present on the surface of remnants of the vitreous base. This tissue extends anteriorly and attaches to the pars plicata of the ciliary body, posterior surface of the iris, or even the pupillary margin.! Traction is exerted in two directions: posteroanterior and circumferential. Because the anterior vitreous base is anchored to the pars plana, the posterior vitreous base, the peripheral retina, and even some pars plana epithelium are pulled both forward and inward, creating a circumferential fold of the retina. A trough of varying width and depth appears anterior to this circumferential fold (Fig. 8). In some eyes, the trough may appear to be closed if the peripheral retina is dragged
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Fig. 4 (Machemer and associates). Proliferative vitreoretinopathy Grade C. Type 2, diffuse contraction with multiple confluent retinal folds.
anteriorly and becomes adherent to the anterior structures, with resulting posterior retraction of the iris.
Method of Grading
Grading takes place by means of a standardized method depicting each type of contraction On a retinal diagram (Fig. 9). The posterior
August, 1991
types of contraction and their location are recorded in the postequatorial portion of the diagram: Type 1, focal contraction (starfold), is depicted by a large X centered On the starfold. Type 2, diffuse contraction, is shown by a group of large Xs. Subretinal proliferation can occur in both the postequatorial and preequatorial parts of the diagram: Type 3, subretinal proliferation, is indicated by a broken black line. The anterior forms of contraction and their location are recorded in the preequatorial portion of the diagram: Type 4, circumferential contraction, is shown by a series of small xs. Type 5, anterior displacement, is depicted like circumferential contraction with arrows pointing anteriorly. Using a retinal diagram, One can quickly determine the grade and type of proliferative vitreoretinopathy. The grading is illustrated in Figure 9. The total numbers of clock hours of traction in the posterior (postequatorial) and the anterior (preequatorial) portion of the diagram are noted separately. The overall extent of proliferative vitreoretinopathy denotes the number of clock hours of involvement by traction affecting the posterior (CP) and anterior (CA) parts of the retina (for example, CP-6, CA-9).
Fig. 5 (Machemer and associates). Proliferative vitreoretinopathy Grade C. Type 3. Left, Subretinal contraction causing a semi-annular fold of the retina on nasal side of optic nerve head while ill-defined motheaten sheets fold its temporal aspect. Right, A high retinal fold is created by partially pigmented subretinal band with retina draped over it.
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Fig. 6 (Machemer and associates). Proliferative vitreoretinopathy Grade C. Type 4, circumferential contraction with proliferation immediately behind insertion of the posterior hyaloid pulling retina centrally, stretching the retina anterior to it and creating radial folds posteriorly. Schematic drawing of situation in nonvitrectomized eye (left) and vitrectomized eye (right). Arrows show direction of pull. A more detailed description of the proliferative vitreoretinopathy can be provided by adding the type of contraction to the grade. For example, the classification CP-6, type I, 2, 3 describes visible postequatorial proliferations (focal, diffuse, subretinal) covering a total of six clock hours. The classification CA-9, type 4, 5 describes preequatorial circumferential proliferations and anterior displacement covering nine clock hours. Because the fovea is the center of the diagram, expressing the extent of the fold in this area in clock hours is difficult. A focal contraction in the macula is judged to represent one clock hour. A diffuse macular contraction covering a larger area is evaluated as if it were slightly shifted to the temporal side. An optional, even more detailed description can be achieved by adding to each type the number of clock hours involved, similar to those in the grades. Also, proliferations of various types can overlap. Expansion of the example CP-6, type I, 2, 3 would be represented as CP-6 type I-I, 2-2, 3-4. In this case the different types all occur within the total extent of the six clock hours. Grade C anterior vitreoretinopathy-9, type 4, 5 would appear as CA-9, type 4-8, 5-3.
Discussion The proposed classification summarized in Tables 1 and 2 has been developed to retain as much as possible of the old classification" and by drawing on the experience of the Silicone Study group and others.v' The major changes in the grading system from the original 1983 Retina Society classification are the distinction between posterior and anterior abnormalities, addition of a description of contraction types, abandoning the description of the configuration of the retinal funnel, while using clock hours instead of quadrants to describe the extent of the abnormality. Although the ophthalmoscopic picture of proliferation effects in the postequatorial portions of the eye was reasonably well described under the old system, preequatorial findings were neglected, especially in eyes that had previously undergone vitrectomy. For this reason Grade C has now been subdivided into posterior and anterior regions in order to allow for a description of the clinical picture and types of contraction in anterior proliferative
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Fig. 7 (Machemer and associates). Proliferative vitreoretinopathy Grade C. Type 4, circumferential contraction. vitreoretinopathy'f (Table 1). More detailed descriptions of the posterior proliferation effect are made possible by adding the contraction types (focal, diffuse, and subretinal contractions). Anterior proliferation effects are more fully described by addition of references to circumferential contraction':" and anterior dis-
August, 1991
placement (Table 2). Because experience has shown little correlation between funnel size and severity or prognosis, Grade D of the previous classification was abandoned. Under the old system, although subretinal proliferations were known as part of the clinical picture, I no consideration was given to their presence.! They have now been included as contraction type 3. Under the revised system, however, still no attempt is made to detail information on these strands, as they are often difficult to define. The Committee chose not to record information regarding the number, size, and location of retinal breaks in this new classification. Their conclusion was that doing so would only complicate the classification. Furthermore, many retinal holes are hidden or purposefully or inadvertently created during surgery, thereby rendering this information of little value. Individual researchers may, of course, opt to include such information in their own case reports. No effort was made to define the level of activity of the proliferative process because present knowledge is insufficient to provide objective measures.
Fig. 8 (Machemer and associates). Proliferative vitreoretinopathy Grade C. Type 5, anterior displacement of the vitreous base. Left, Schematic drawing shows how peripheral retina is pulled forward by fibrous adhesions between vitreous base, ciliary body, and iris to form a retinal trough in a previously vitrectomized and buckled eye. (Courtesy of Springer Verlag, 1988; Freeman and Tolentino, Proliferative Vitreoretinopathy, p. 25, Fig. 5.) Right, The most extreme fundus periphery with fibrous tissue in the pars plana area (arrow) causing radial folds (x) in detached retina overlying a circumferential buckle.
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Fig. 9 (Machemer and associates). Retinal diagram to depict the various types of fullthickness retinal folding.
Type 1: focal = X Type 2: diffuse = X X X Type 3: subretinal = - Type 4: circumferential
=
XXX)(
Type 5: anterior displacement
t t =xxxx
In an effort to promote generalized use of this new classification, the Committee has tried to keep it as simple as possible. The committee approach in formulating a classification is advantageous in that a common denominator must be found for differing individual opinions. A classification is best built on ophthalmoscopic and biomicroscopic observations rather than on interpretation of the visible findings. The Committee presents this new classification in the full awareness that it only represents present knowledge and may well need future revisions.
References 1. Machemer, R.: Pathogenesis and classification of massive periretinal proliferation. Br. ]. Ophthalmol. 82:737, 1978. 2. The Retina Society Terminology Committee: The classification of retinal detachment with prolif-
erative vitreoretinopathy. Ophthalmology 90:121, 1983. 3. Lean, ]. S., Stern, W. A., Irvine, A. R., Azen, S. P., and The Silicone Study Group: Classification of proliferative vitreoretinopathy used in the Silicone Study. Ophthalmology 96:765, 1989. 4. Heimann, K., and Wiedemann, P.: Cologne classification of proliferative vitreoretinopathy. In Heimann, K., and Wiedemann, P. (eds.): Proliferative Vitreoretinopathy. Heidelberg, Kaden Verlag, 1989, pp. 148 and 149. 5. Freeman, H. M., Elner, S. G., Tolentino, F. I., Schepens, C. L., Elner, V. N., and Albert, D. M.: Anterior PVR. Part I. Clinical findings and management. In Freeman, H. M., and Tolentino, F. I. (eds.): Proliferative vitreoretinopathy. New York, Springer Verlag, 1988, pp. 22-33. 6. Lewis, H., and Aaberg, T. M.: Anterior proliferative vitreoretinopathy. Am. ]. Ophthalmol. 105:277, 1988. 7. Elner, S. G., Elner, V. M., Diaz-Rohena, R., Freeman, H. M., Tolentino, F. I., and Albert, D. M.: Anterior proliferative vitreoretinopathy. Clinicopathologic, light microscopic and ultrastructural findings. Ophthalmology 95:1349, 1988.
