|COMMUNITY EYE CARE
|Year : 2000 | Volume
| Issue : 2 | Page : 153-8
Visual outcome following cataract surgery in rural punjab.
R Anand, A Gupta, J Ram, U Singh, R Kumar
Department of Ophthalmology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
Department of Ophthalmology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012
Source of Support: None, Conflict of Interest: None
In a cluster sample survey in rural areas of Punjab visual outcome after cataract surgery was assessed. Three hundred patients (428 cataract operated eyes) were included in the study from 24 sampled villages. The mean age at cataract extraction was 61.70 +/- 9.82 years. The average interval since the cataract surgery was 7.05 +/- 5.86 years (range 0.11-32 years). Of the 428 operated eyes, 72 (16.82%) were blind (VA < 3/60), 162 (37.85%) had low visual acuity (VA 3/60-< 6/18) and 194 (45.33%) eyes gained good visual acuity (VA > or = 6/18). Cataract surgery related complications were the principal causes leading to blindness in 50 of 72 eyes; these included corneal oedema, (17/72;23.3%), retinal detachment (14/72;19.4%), and aphakic glaucoma (13/72;18.05%). This study emphasizes the need to improve the qualitative aspect of cataract surgery including long-term follow up in rural India.
Keywords: Aged, Blindness, epidemiology, etiology, Cataract, epidemiology, Cataract Extraction, adverse effects, Comparative Study, Female, Humans,
|How to cite this article:|
Anand R, Gupta A, Ram J, Singh U, Kumar R. Visual outcome following cataract surgery in rural punjab. Indian J Ophthalmol 2000;48:153
The World Health Organisation - National Program for Control of blindness (WHO-NPCB) survey (1986-89) suggests that 80.1% of the 22 millions eyes/12 million blind individuals in India are suffering from cataract. The annual output of cataract intervention program is measured only in terms of number and the qualitative aspect is very often ignored. Every one of the 2.2 million cataract surgeries performed each year in India does not change a cataract blind into a sighted person. The indicator commonly used to measure the qualitative output is the success rate, i.e., the percentage of operations that result in restoration of sight in the operated eye in a particular year. Various studies have shown success rates of cataract surgery (best corrected visual acuity ≥ 6/18) range from 28% to 92%. [3,4] Different success rates have been observed in camp and hospital-based surgeries. [4,5] However, there are very few studies elucidating the causes of blindness in the aphakic population.[6-9] Long-term follow up and thorough examination is required to determine the late complications of surgery. This study was designed to estimate the prevalence and main causes of blindness following cataract surgery in the rural areas of Punjab.
| Materials and Methods|| |
| Sampling process|| |
The sample size of 300 was estimated assuming a post-cataract surgery blindness rate of 15% (as reported by Verma et al), at 5% precision (95% confidence interval) to determine the visual outcome of cataract surgery by cluster sample design. The study was carried out between October 1996 and October 1997.
Roopnagar district, one of the rural areas of Punjab, was chosen because of feasibility (this district is located within 40 kms of union territory of Chandigarh). A village was defined as a cluster. In the first step all the villages in the district were listed with their population. The cumulative population for every village was calculated. The total population was divided by the number of villages to be surveyed, i.e., 15, to arrive at a sampling interval. Random samping was used to select the first village. The next village was selected by adding the sampling interval to the random population number. A similar process was used to select the other sample villlages. The total population of the sampled villages was 29,300.
The survey in the sample villages was carried out in two phases. In the first phase trained field workers identified 307 cataract-operated patients using multiple key informants a few days prior to the visit by the ophthalmologist. In the second phase these patients were requested to assemble at a fixed place and time in the village. On the appointed day the village was visited and examination was carried out by the ophthalmologists. Out of 307 patients surveyed in the first phase, 300 were examined in the second phase. In the last village the survey was carried out till 300 patients were completed for the study. A village resident was defined as any individual staying in the said village for more than six months. Visitors and guests were excluded from the study.
| Examination procedure|| |
All the patients were interviewed and examined by a trainee ophthalmologist and the findings were confirmed by a consultant ophthalmologist. History was recorded with regard to the time and place of surgery, pre-cataract vision, (patient's subjective assessment), any episode of pain, redness and watering just prior to cataract surgery, postoperative visual gain, use of aphakic glasses and any prior ocular surgery or trauma. History was specifically elicited to rule out pre-existing corneal pathology and glaucoma. Visual acuity was recorded with Snellen's distant vision chart of illiterate 'E' type kept at a distance of 6 meters in shaded daylight. Visual acuity was recorded separately for each eye using aphakic glasses with and without pin hole. The anterior segment was examined using flashlight and binocular magnifying loupe especially to look for cataract section, corneal oedema/opacity, fibrous/epithelial downgrowth, peaked/distorted pupil, aphakia/pseudophakia or any other causes of blindness/ low vision in the anterior segment. The posterior segment was examined with direct ophthalmoscope after pupillary dilation to look for age-related macular degeneration (AMD), retinal Detachment (RD), glaucomatous cupping or any other cause of blindness/low vision in the posterior segment. The intraocular pressure (IOP) was recorded before dilatation in each eye using an electronic tonometer, Proton (Tomey PRO-100, Cambridge, USA). Selected patients were called to the base hospital for further management when required.
| Terminology used|| |
- Blindness: corrected visual acuity of <3/60 in the cataract-operated eye.
- Low vision: corrected visual acuity of 3/60 to <6/18 in the cataract-operated eye.
- Good vision: corrected visual acuity of≥6/18 in the cataract-operated eye.
| Diagnosis|| |
Each cataract operated eye was diagnosed based on history and clinical finding. As there could be more than one aetiology for blindness /low vision in a particular eye, all the causes were listed and the principal cause leading to blindness/low vision was determined. The principal cause was then categorized into anterior and posterior segment lesion. The above causes were further categorized into cataract surgery-related and non related causes.
Cataract surgery related causes
- Complicated section, i.e., vitreous in section, peaked pupil, epithelial/ fibrous downgrowth.
- Corneal oedema / opacity
- Aphakic glaucoma
- Posterior capsular opacification
- Retinal detachment
- Cystoid macular oedema
- Vitreous haze
- Unilateral optic atrophy
Non-cataract surgery related causes
- Corneal opacity prior to cataract surgery with/without history of injury.
- Age-related macular degeneration (AMD)
- Disciform scar
- Glaucomatous optic atrophy
- Optic atrophy (nonglaucomatous)
- Chorioretinal degeneration
- Macular hole
| Results|| |
This study evaluated visual acuity in 300 patients (428 operated eyes) following cataract surgery. There were 159 males (53%) and 141 females (47%). The mean age of the patients at the time of cataract surgery was 61.79±9.82 years. The average interval between cataract surgery and this survey was 7.04±5.86 (range 0.11-32) years. There were 16 patients (5.33%) in the 41- 50 years age group, 62 patients (20.67%) in the 51-60 years age group, 128 patients (42.67%) in the 61-70 years age group and 94 patients (31.33%) were above 70 years of. age. One hundred and seventy two patients (57.3%) were unilateral aphakic while 128 (42.66%) were bilateral aphakic. One hundred and ninety two surgeries (44.86%) were done in eye camps, 97 surgeries (28.62%) in rural hospital, 66 surgeries (15.24%) in private clinics, 44 surgeries (10.28%) in a government hospital and 29 surgeries (6.78%) in a tertiary-care hospital.
Of the 428 operated eyes 194 (45.3%) gained good vision, 162 eyes (37.85%) had low vision and 72 eyes (16.82%) were blind [Table:1]. This table highlights the importance of refractive correction in the cataract operated eyes. Without adequate refractive correction only 140 (32.7%) of the operated eyes had visual acuity of 6/18 or better. Refractive correction with aphakic glasses and pinhole enabled 194 (45.3%) of the operated eyes to see 6/18 or better. Among unilaterally operated patients, 94 (54.65%) eyes had visual acuity of≥6/18 while in bilaterally operated patients 74 (57.81%) eyes had visual acuity of 6/18 or better in the better eye with aphakic glasses and pinhole. Among the unilaterally operated patients 13 (13/172; 7.56%) were blind and among bilaterally operated patients, 9 (9/128; 7.03%) were blind postoperatively.
At the time of survey spectacles were not used by 39 patients (46 eyes) and the main reason for not using spectacles was unsatisfactory visual improvement in the operated eyes [Table:2]. In this group 33 of the operated eyes (33/46; 70%) had corrected visual acuity of 6/60 or less.
Causes of blindness were categorized into cataract surgery-related and non-cataract surgery-related causes. There were 72 blind eyes; in 50 eyes (50/72; 69.4%) the blindness was related to the cataract surgery complications and in remaining 22 eyes (22/72; 30.5%) the blindness was not related to cataract surgery complications. Among the surgery-related complications foremost was corneal oedema followed by retinal detachment and aphakic glaucoma. Among the non-cataract surgery-related causes the most common was traumatic corneal opacity followed by pre-existing glaucoma, band-shaped keratopathy and climatic droplet keratopathy. Pterygium and macular hole were other non-surgery- related causes of blindness [Table:3]. These causes were also studied in relation to the time since cataract surgery. Corneal opacity and oedema were more common in the longer postoperative interval whereas optic atrophy and endophthalmitis were noted in the early post-operative interval. The visual acuity vis-…-vis postoperative interval following cataract surgery was evaluated. It was noted that there was a deterioration in visual outcome with longer interval following surgery. In patients with one year interval following cataract surgery only 2 of 61 (3.3%) eyes were blind and 28 (45.9%) eyes had visual acuity of ≥6/18, whereas among patients with more than 10 years interval following cataract surgery 21 of 97 (21.62%) eyes were blind and 31 (31.9%) eyes had visual acuity of ≥6/18 [Table:4].
The visual outcome vis-…-vis the place of surgery was analysed [Table:5]. While most eyes (192/428; 44.86%) were operated in eye camps, the distribution of good vision (acuity ≥ 6/18) was uniformly distributed between various locations of surgery.
| Discussion|| |
Cataract blindness is the main target of National Program for Control of Blindness in India and most of the resources are diverted for the elimination of the same. A lot of emphasis is laid upon increasing the coverage of cataract surgery. It includes organisation of eye camp surgeries by government and non-government organisations. Considering the immense load of cataract blindness and limited resources it is not unlikely that the qualitative aspect could sometimes be ignored. This is particularly true while considering the community at large. With increase in awareness of the quality of life in general and quality of eye care in particular various reports have been published regarding the poor outcome of cataract surgery at the community level in India [3, 5, 6, 9, 11] as well as in other developing countries like Nepal and China. [7, 8, 12]
Cataract surgery outcomes at community level in various regions of India have recently been published; they include the states of Andhra Pradesh, Karnataka, Maharashtra, Gujarat, Madhya Pradesh, Haryana, and Uttar Pradesh. Some of these studies are population based [9,5] whereas others are camp or hospital based. [4, 6, 11]
In order to assess the quality of cataract intervention for the community at large, sample selection is of great importance. A hospital or camp-based sample can give an estimate of the outcome but it may not be representative of the community or the population at large. While population-based studies of cataract surgery outcome in south and central India [9,5] are available similar reports from north India are lacking. Most of these studies highlight poor visual outcome following cataract surgery, particularly when performed in eye camps or in the rural areas.
The primary aim of this study was to evaluate the prevalence and causes of blindness related to cataract surgery in the rural Punjab. We carried out a population based study of patients from the rural population irrespective of the place of surgery. The sample of patients had enough power to yield a statistically valid outcome. Village bias and patient bias were carefully eliminated using cluster sampling. Detailed ophthalmological examination was carried out by ophthalmologists to ascertain the principal causes leading to blindness. Cataract surgery-related causes of. blindness were identified and distinguished from non-cataract surgery-related causes thereby emphasizing the qualitative outcome of cataract surgery. Average interval following cataract surgery was 7.05±5.86 years, which is much longer compared to some of the previous studies [4, 6, 11, 13] with postoperative interval of 6 weeks to one year.
In the present study 72 of 428 (16.82%) cataract-operated eyes were blind. Obviously this blindness rate is unacceptably high considering that the cataract surgery is among one the most successful surgeries carried out with reported failure (blindness) rate between 1.27% and 4.34%. [4,13] In other studies, [6, 7, 11] the incidence of blindness varies from 7.26% to 15.86%. The study by Goyal et al has reported a very high blindness rate of 34.9% in the operated eyes in. India. Their study mentioned various socio-demographic, economic and behavioural factors of the patients attending the eye camps in rural India, but did not mention the causes of blindness. In the Nepal study Henning et al have reported blindness rate of 1.27%, but 314 of 1000 operated patients had only one month follow up. In the study by Reidy et al the blindness rate was 4.34%, but 9 of 493 patients with pre-existing ocular diseases such as corneal opacity and glaucoma were excluded from the study. Hence the low blindness reports of Reidy and Henning et al should be interpreted with caution. [Table:6] summarises cataract surgery outcome in various recent studies from India and other developing Asian countries (Nepal and China).
This study was neither surgeon/institution specific nor time period specific. The outcome of the cataract surgery was assessed vis-…-vis the place and time since surgery. Little less than half of surgeries (192/428; 44.86%) were done in the eye camps. Considering the lack of adequate facilities in these centers the results are expected to be suboptimal. But it was surprising that even in the hospitals or private clinics in these areas the results were poor. Limburg et al have compared the visual outcome in camp and hospital operated cataract patients in the states of Maharashtra, Karnataka and Gujarat. They have found poor visual outcome (visual acuity <6/60) almost twice as common in camp operated patients compared to the hospital operated patients.
In our study the majority, 284 of 300 (94.7%) patients were unaware of the surgeon's experience; this could have a role in the visual outcome of the surgery. It is to be noted that in the studies [4,13] with low blindness rates all the patients were operated upon by experienced surgeons; in contrast to studies reporting higher blindness rates [3, 5, 6, 11] where the patients were operated by ophthalmologists with less uniform experience. The surgeon's experience is likely to be one of the important factors in the final outcome. Recently in a clinical trial in south India comparing extracapsular cataract extraction versus intracapsular cataract extraction the blindness rate was less than 1% following both the surgical procedures. However, these results may not be achieved in a large scale community level surgical practice where the facilities are less adequate than a tertiary-care eye hospital.
There are very few studies regarding causes of low vision/blindness following cataract surgery. Our study suggests that in 50 of 72 blind eyes (68%) causes of blindness are related to cataract surgery-complications. Among these causes corneal pathology was responsible in 33 eyes (45%) and glaucoma in 17 eyes (23%) [Table:7]. These findings are similar to the results of Verma et al (corneal oedema 43% and glaucoma 17%). In the studies by Dandona et al posterior segment complications were the main cataract surgery-related cause of blindness.
In this study RD was noted in 14 (19.2%) and clinically cystoid macular oedema (CME) in 4 (5.5%) operated eyes. These complications are only incompletely reported. [9,11] This could be due to short post-operative interval or patients lost to follow up. Both RD and CME are known complications of intracapsular (ICCE) cataract extraction. Since ICCE is a more common technique of cataract surgery in eye camps these long-term risks should not be ignored. [9,16]
At present the success rate of cataract surgery in rural populations is unacceptably low. Majority of causes of blindness following cataract surgery are related to surgical complications. In experienced hands these complications can be minimized with better outcome even in the rural areas. In order to improve the quality of cataract surgery we must analyse the surgical outcome in a population-based study at a regular interval and try to learn from the past mistakes. A complicated cataract surgery may further add to the pool of blindness instead of reducing the blindness burden. These complicated cases are either irreversibly blind or more difficult to treat than cataract surgery alone.
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Jose R, Bachani D. World Bank Assisted Cataract Blindness Control Project. Indian J Ophthalmol
Limburg H, Kumar R, Bachani D. Monitoring and evaluating and cataract intervention in India. Br J Ophthalmol
Goyal M, Gupta SK, Verma L, Murthi GVS. Socio-demographic parameters of utilization of camp based cataract surgery in rural India. Asia Pacific J Ophthalmol
Reidy A, Mehra V, Minassian D, Mahashabdc S. Outcome of cataract surgery in central India: A longitudinal follow up study. Br J Ophthalmol
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