Article Text

Sutureless cataract surgery with nucleus extraction: outcome of a prospective study in Nepal
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1. A Hennig1,
2. J Kumar1,
3. D Yorston2,
4. A Foster3
1. 1Lahan Eye Hospital, Nepal
2. 2Moorfields Eye Hospital, London, UK
3. 3London School of Hygiene and Tropical Medicine, London, UK
1. Correspondence to: Dr Albrecht Hennig, Lahan Eye Hospital, Nepal; ahennig{at}mos.com.np

## Abstract

Aim: To report the short and medium term outcome of a prospective series of sutureless manual extracapsular cataract extractions (ECCE) at a high volume surgical centre in Nepal.

Methods: Cataract surgery was carried out, on eyes with no co-existing diseases, in 500 consecutive patients who were likely to return for follow up. The technique involved sclerocorneal tunnel, capsulotomy, hydrodissection, nucleus extraction with a bent needle tip hook, and posterior chamber intraocular lens (PC-IOL) implantation according to biometry findings. Surgical complications, visual acuity at discharge, 6 weeks, and 1 year follow up, and surgically induced astigmatism are reported.

## DISCUSSION

Many patients travel considerable distances to obtain treatment at Lahan, and they usually cannot return for postoperative examinations. In order to obtain adequate follow up in such difficult circumstances, only 500 patients from closer districts out of a total of 14 500 were selected. All patients with known pre-existing eye disease were excluded. The authors believe that the selection of local patients has not biased the results, as there is no evidence that district of residence influences the outcome of cataract surgery.

### Surgical outcome

Sutureless cataract surgery is more difficult than conventional sutured ECCE and PC-IOL. The preparation of a relatively long and narrow sclerocorneal tunnel, handling the instruments, and removing the entire nucleus all require good surgical skills and additional training. However, once the technique is mastered the surgery is faster and less expensive, because no sutures are required. When performed by an experienced surgeon, the complication rate is low—there was only one posterior capsule rupture in this study. In Japan, posterior capsule rupture occurred in 5.9% of eyes, and this was thought to be the result of learning the new technique.9

Bleeding from the wound into the AC occurred in 9.4% of operations, which prolonged the surgery by another 5 minutes. Hyphaema was the most common complication resulting in four additional intraocular procedures and 36 additional patient days in hospital.

Two eyes suffered persistent corneal oedema. Removal of the nucleus through a scleral tunnel can be traumatic. Endothelial damage can be minimised by nucleus extraction from within the capsular bag rather than displacing the nucleus into the AC. This reduces manipulation in the AC, and avoids contact between the nucleus and the endothelium. Endothelial trauma can be reduced further by the use of intracameral viscoelastics before extraction of the nucleus.19

Eighty (16.0%) of cases had pre-existing central posterior capsule plaques; however, only 10 of the 80 cases had an acuity less than 6/18 at discharge attributable to the plaque. The frequency and location of this type of posterior capsule opacification corresponds with a previous histopathological study on human crystalline lenses from our centre.20

### Visual outcome

Before surgery nearly all eyes (96.8%) were severely visual impaired or blind. This was reduced to less than 1% by discharge.

In comparison with sutured manual ECCE and PC-IOL, sutureless surgery provides fast visual recovery. In our patients, 76.8% had an unaided acuity of 6/18 or better at discharge (Table 2). By comparison, in a randomised controlled trial of standard ECCE and PC-IOL and intracapsular cataract extraction and aphakic glasses, only 57.5% of the ECCE and PC-IOL eyes achieved an unaided acuity of 6/18 or better by 2 months after surgery.15 However, another study of sutureless ECCE in Nepal showed that only 58.3% of eyes obtained an uncorrected vision of 6/18 or better at 8 weeks.10

The low incidence of poor visual outcome (less than 6/60) is due to the low rate of operative complications, and to the exclusion of eyes with known comorbidity.

There was a statistically significant reduction (6.3%) in the number of eyes achieving 6/18 or better without correction between discharge and 6 weeks’ follow up. A further slight decrease (5.6%) between 6 weeks and 1 year was not significant. The most likely cause for the worsening uncorrected acuity is an increase in surgically induced astigmatism (Table 4).

In another study of sutured ECCE and PC-IOL, the proportion of eyes with an uncorrected vision of 6/18 or better increased from 57.5% at 2 months to 83.7% by 1 year.15

Although keratometry was not performed at discharge, it seems likely that the worsening of unaided acuity is the result of increasing against the rule astigmatism. Between 6 weeks and 1 year, the increase in astigmatism and the corresponding decrease in unaided visual acuity is small, suggesting that, in most cases, the wound is stable by 6 weeks after surgery.

In nearly two thirds of the eyes with an unaided acuity less than 6/18, the cause of reduced vision was astigmatism. We tried to limit the astigmatism by placing the incision as far behind the limbus as possible, and by keeping the width of the sclerocorneal tunnel to a minimum. However, in eyes with large nuclei, the incision had to be 8 mm wide in order to extract the nucleus. Even these larger tunnel openings remained self sealing without sutures.

The mean induced astigmatism of 1.4D is similar to other reports from industrialised countries.9,19

It is known that uncorrected refractive error is a common cause of poor outcome following cataract surgery in developing countries. The cost of glasses, and, in some countries, the lack of expertise to prescribe and manufacture high quality spectacles, limits their use. If the outcome of cataract surgery globally is to improve, it is imperative to find means of improving uncorrected postoperative visual acuity, as well as best corrected vision. We believe that the technique of sutureless ECCE may help to increase the number of patients with good uncorrected vision.

Refinements in the surgical technique may further reduce refractive error as a cause of poor vision after this type of surgery. For example, a single radial stitch may reduce against the rule astigmatism in sutureless ECCE.21 Alternatively, a temporal or oblique incision may be performed in eyes that have against the rule astigmatism preoperatively. In this study, 65.4% of eyes had against the rule astigmatism before surgery (Table 4).

### Keratometry and A-scan

For keratometry we used an automated keratometer, which requires the patient’s cooperation to fixate on an illuminated target. Many patients with advanced cataract were unable to focus on this symbol, making it difficult to obtain reproducible keratometer readings. In such cases we performed keratometry on 162 fellow eyes with less cataract, and assumed that the average corneal power was similar in both eyes.

The time required for preoperative biometry was greater than for the surgery itself. In this population axial ametropia appears to be relatively uncommon, although patients with known high myopia were excluded. At least 78% of eyes would have been within 1D of emmetropia with a 22D lens. Further study is required to weigh the visual benefits of biometry against the extra costs and time required in rural settings with a high surgical volume.

### Cost of surgery

It has been shown that, in Europe, phacoemulsification with a foldable IOL is less costly than manual ECCE and IOL.4 However, this analysis did not include the capital cost of a phacoemulsifier, and used a PMMA IOL costing £38.00. In developing countries, high quality, locally made IOLs can be purchased for less than £3.00, but high quality foldable IOLs must be imported, and are much more expensive. The use of locally produced consumables minimises the cost of surgery. Until phacoemulsification consumables, and foldable IOLs, can be manufactured in developing countries, phacoemulsification will be too costly for the majority of cataract patients.

This study shows that sutureless manual cataract surgery can be a safe and effective technique in the hands of an experienced surgeon in areas with a high demand for cataract surgery, including advanced cataract with large nuclei.

The surgical technique is more demanding than sutured ECCE and PC-IOL and requires additional surgical training. However, once this technique is mastered it provides a good visual outcome and fast visual recovery. Further work is required to reduce the incidence of peroperative hyphaema and postoperative astigmatism.

## Footnotes

• Series editors: W V Good and S Ruit