1110
PHOTOCOAGULATION IN TREATMENT OF DIABETIC MACULOPATHY Interim
Report of a Multicentre Controlled Study*
A multicentre randomised controlled trial of xenon-arc photocoagulation for diabetic maculopathy is reported. This interim account reports the visual-acuity results of those who were followed up for up to three years. 76 patients were seen after one year, 44 after two years, and 25 after three years. Initially each patient had two similarly affected eyes of which one was treated. The treated eyes retained significantly better visual acuity than the untreated ones. Treated eyes deteriorated by 1 or 2 Snellen lines significantly less often than did untreated eyes. 8 treated and 18 untreated eyes became blind. Prognosis was best in those with initial visual acuity of 6/24 or better.
Summary
Introduction DIABETIC blindness in
retinopathy is the commonest cause of England and Wales for the age-group fifty
sixty-four years. It is also the commonest cause of all newly registered blindness.’ Diabetic retinopathy can be classified into two broad categories. Background or "simple" retinopathy consists predominantly of microaneurysms, haemorrhages, hard exudates, and retinal oedema. Proliferative or "malignant" retinopathy2 is characterised by newly formed vessels and associated fibrous tissue. Proliferative retinopathy has the worse prognosis for vision,3but background retinopathy is far more common, especially in diabetics aged fifty or more. Involvement of the macula by the lesions of background retinopathy can cause serious visual impairment, and application of the figures of Caird and GarrettS to the large numbers of older diabetics makes maculopathy numerically the more serious cause of diabetic blindness. During the past ten years photocoagulation has been used increasingly in the treatment of diabetic retinopathy. There is, as yet, no report of a controlled, randomised study which proves the efficacy of this treatment for proliferative retinopathy, but there is one detailed report6 indicating the usefulness of photocoagulation in the treatment of diabetic maculopathy. This paper is an interim report of a multicentre photocoagulation trial, sponsored by the British Diabetic Association, of xenon-arc photocoagulation for diabetic maculopathy. to
Patients and Methods
Definition Maculopathy was defined ophthalmoscopically by the presence of haemorrhages, exudates, and macular oedema associated with a corrected visual acuity of 6/9 or less on the Snellen test type, or, in patients with a visual acuity better than 6/9, if the edge of a ring-shaped (circinate) formation of hard exu-
Patients Patients were recruited from hospital diabetic clinics. Most of the Hammersmith/Moorfields group had been referred by physicians and ophthalmologists from other hospitals to the special retinopathy clinics run at these hospitals. Few patients presented in the ophthalmology departments because of visual symptoms. Patients were admitted to this trial only if both eyes were similarly affected. Similarity was considered acceptable when visual acuity did not differ by more than two lines of the Snellen test type, and when the same observable features of retinopathy were present and were of approximately the same degree of severity (or within two Hammersmith Hospital
grades7). Patients were excluded from the trial if: (1.) They were unlikely to survive one year. (2.) There was intercurrent disease of the eyes or visual pathways likely to affect visual acuity or clarity of the media during the period of observation.
(3.) There
was more
than
a
wisp of fibrous retinitis proliferans in the
fundus.
(4.) There was macular scarring. (5.) There was detachment or retinoschisis fundus. (6.) The media
were not
clear
in the
temporal half of the
enough for fundus photography and un-
impeded central vision. Methods
Randomisation.-After admission of a patient to the trial the eye for treatment was determined by opening a sealed envelope, previously randomised between eyes by the coordinating centre. The envelopes carried serial numbers and were opened strictly in numerical order at each centre. Treatment.-The eye chosen for treatment had xenon-arc photocoagulation, usually under local (retrobulbar) anxsthesia. The apparatus used was the Zeiss (Oberkochen) or the O’Malley light coagulator. Treatment was given according to the judgement of the ophthalmologist in charge. The mode of treatment included: (a) coagulation of lesions lateral to the macula, (b) diffuse photocoagulation to include all visible lesions outside the main temporal vessels, and (c) photocoagulation of the centre of circinate rings of hard exudates, if this was not located at the macula, or the papillomacular nervefibre bundle. At first (a) and (c) were used most frequently, but in later patients a combination of (a) and (b) or (b) and (c) was commonest. 60% of patients had more than one treatment session, Data collected.-The best corrected visual acuity was recorded before treatment and yearly thereafter. The disc and macula were photographed yearly and were graded centrally by the coordinator and an unbiased, specially trained observer (nurse/technician) using the Hammersmith Hospital grading system.’ Details of medical management, diabetic control, and general health were also recorded. Only visual-acuity changes will be presented here; a fuller analysis will appear in the final report of the trial. Analysis.-Visual acuities were transformed into a numerical scale, as reported previously with slight modification.8 The conversion was simple--e.g., 6/6=1 ; 6/9=2, progressing to "no perception of light" =10 (table i). The paired t test was used to compare the change of visual acuity in the treated and the untreated eye. McNemar’s test’ was used at each yearly follow-up to compare the number of
dates encroached on the macula. TABLE I—CODING FOR VISUAL ACUITY
’Coordinating
Committee: Mr H. CHENG, Dr EvA M. KOHNER, Prof.
KEEN, Mr R. K. BLACH, and Mr D. W. HILL. Statisticians: Prof. P. ARMITAGE and Miss JUDITH M. BAILEY. Participating ophthalmologists: Mr BLACH, London; Mr H. B. CHAWLA, Edinburgh; MrCHENG, London; Mr E. W. DAVIES, London; Mr N. R. GALLOWAY, Nottingham; Mr A. M. HAMILTON, London; Dr M. ODLAND, Bergen, Norway; Mr J. RICHARDSON, Newcastle; Mr K. RUBINSTEIN, Birmingham; and Mr D. M. WATSON, London. H.
CF - count
IIM--hancl
fingers
movement
P1
=perception of light perception of light
nim.-no
1111 TABLE II—AGE AND INITIAI. VISUAL ACUITY
TABLE V-DIFFERENCE IN DETERIORATION
d=mean difference in deterioration. For example, at one-year follow-up=(where VA=visual acuity, u and t=untreated and treated, and 0 and 1=initial and one-year values.
VAu1VAu0)(VAt1VAt0) TABLE III—KNOWN DURATION OF DIABETES AND M.I.V.A.
"fair" (6/12, 6/18, or 6/24), or "poor" (6/36 or less), deterioration of the untreated eyes exceeded that in the treated most in the "fair" group. (For good M.I.V.A. p
PHOTOCOAGULATION IN TREATMENT OF DIABETIC MACULOPATHY Interim
Report of a Multicentre Controlled Study*
A multicentre randomised controlled trial of xenon-arc photocoagulation for diabetic maculopathy is reported. This interim account reports the visual-acuity results of those who were followed up for up to three years. 76 patients were seen after one year, 44 after two years, and 25 after three years. Initially each patient had two similarly affected eyes of which one was treated. The treated eyes retained significantly better visual acuity than the untreated ones. Treated eyes deteriorated by 1 or 2 Snellen lines significantly less often than did untreated eyes. 8 treated and 18 untreated eyes became blind. Prognosis was best in those with initial visual acuity of 6/24 or better.
Summary
Introduction DIABETIC blindness in
retinopathy is the commonest cause of England and Wales for the age-group fifty
sixty-four years. It is also the commonest cause of all newly registered blindness.’ Diabetic retinopathy can be classified into two broad categories. Background or "simple" retinopathy consists predominantly of microaneurysms, haemorrhages, hard exudates, and retinal oedema. Proliferative or "malignant" retinopathy2 is characterised by newly formed vessels and associated fibrous tissue. Proliferative retinopathy has the worse prognosis for vision,3but background retinopathy is far more common, especially in diabetics aged fifty or more. Involvement of the macula by the lesions of background retinopathy can cause serious visual impairment, and application of the figures of Caird and GarrettS to the large numbers of older diabetics makes maculopathy numerically the more serious cause of diabetic blindness. During the past ten years photocoagulation has been used increasingly in the treatment of diabetic retinopathy. There is, as yet, no report of a controlled, randomised study which proves the efficacy of this treatment for proliferative retinopathy, but there is one detailed report6 indicating the usefulness of photocoagulation in the treatment of diabetic maculopathy. This paper is an interim report of a multicentre photocoagulation trial, sponsored by the British Diabetic Association, of xenon-arc photocoagulation for diabetic maculopathy. to
Patients and Methods
Definition Maculopathy was defined ophthalmoscopically by the presence of haemorrhages, exudates, and macular oedema associated with a corrected visual acuity of 6/9 or less on the Snellen test type, or, in patients with a visual acuity better than 6/9, if the edge of a ring-shaped (circinate) formation of hard exu-
Patients Patients were recruited from hospital diabetic clinics. Most of the Hammersmith/Moorfields group had been referred by physicians and ophthalmologists from other hospitals to the special retinopathy clinics run at these hospitals. Few patients presented in the ophthalmology departments because of visual symptoms. Patients were admitted to this trial only if both eyes were similarly affected. Similarity was considered acceptable when visual acuity did not differ by more than two lines of the Snellen test type, and when the same observable features of retinopathy were present and were of approximately the same degree of severity (or within two Hammersmith Hospital
grades7). Patients were excluded from the trial if: (1.) They were unlikely to survive one year. (2.) There was intercurrent disease of the eyes or visual pathways likely to affect visual acuity or clarity of the media during the period of observation.
(3.) There
was more
than
a
wisp of fibrous retinitis proliferans in the
fundus.
(4.) There was macular scarring. (5.) There was detachment or retinoschisis fundus. (6.) The media
were not
clear
in the
temporal half of the
enough for fundus photography and un-
impeded central vision. Methods
Randomisation.-After admission of a patient to the trial the eye for treatment was determined by opening a sealed envelope, previously randomised between eyes by the coordinating centre. The envelopes carried serial numbers and were opened strictly in numerical order at each centre. Treatment.-The eye chosen for treatment had xenon-arc photocoagulation, usually under local (retrobulbar) anxsthesia. The apparatus used was the Zeiss (Oberkochen) or the O’Malley light coagulator. Treatment was given according to the judgement of the ophthalmologist in charge. The mode of treatment included: (a) coagulation of lesions lateral to the macula, (b) diffuse photocoagulation to include all visible lesions outside the main temporal vessels, and (c) photocoagulation of the centre of circinate rings of hard exudates, if this was not located at the macula, or the papillomacular nervefibre bundle. At first (a) and (c) were used most frequently, but in later patients a combination of (a) and (b) or (b) and (c) was commonest. 60% of patients had more than one treatment session, Data collected.-The best corrected visual acuity was recorded before treatment and yearly thereafter. The disc and macula were photographed yearly and were graded centrally by the coordinator and an unbiased, specially trained observer (nurse/technician) using the Hammersmith Hospital grading system.’ Details of medical management, diabetic control, and general health were also recorded. Only visual-acuity changes will be presented here; a fuller analysis will appear in the final report of the trial. Analysis.-Visual acuities were transformed into a numerical scale, as reported previously with slight modification.8 The conversion was simple--e.g., 6/6=1 ; 6/9=2, progressing to "no perception of light" =10 (table i). The paired t test was used to compare the change of visual acuity in the treated and the untreated eye. McNemar’s test’ was used at each yearly follow-up to compare the number of
dates encroached on the macula. TABLE I—CODING FOR VISUAL ACUITY
’Coordinating
Committee: Mr H. CHENG, Dr EvA M. KOHNER, Prof.
KEEN, Mr R. K. BLACH, and Mr D. W. HILL. Statisticians: Prof. P. ARMITAGE and Miss JUDITH M. BAILEY. Participating ophthalmologists: Mr BLACH, London; Mr H. B. CHAWLA, Edinburgh; MrCHENG, London; Mr E. W. DAVIES, London; Mr N. R. GALLOWAY, Nottingham; Mr A. M. HAMILTON, London; Dr M. ODLAND, Bergen, Norway; Mr J. RICHARDSON, Newcastle; Mr K. RUBINSTEIN, Birmingham; and Mr D. M. WATSON, London. H.
CF - count
IIM--hancl
fingers
movement
P1
=perception of light perception of light
nim.-no
1111 TABLE II—AGE AND INITIAI. VISUAL ACUITY
TABLE V-DIFFERENCE IN DETERIORATION
d=mean difference in deterioration. For example, at one-year follow-up=(where VA=visual acuity, u and t=untreated and treated, and 0 and 1=initial and one-year values.
VAu1VAu0)(VAt1VAt0) TABLE III—KNOWN DURATION OF DIABETES AND M.I.V.A.
"fair" (6/12, 6/18, or 6/24), or "poor" (6/36 or less), deterioration of the untreated eyes exceeded that in the treated most in the "fair" group. (For good M.I.V.A. p
