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Original Article

Manual Small Incision Cataract Surgery in Eyes with White Cataracts

Venkatesh, Rengaraj DNB; Das, Manoranjan DNB; Prashanth, Sadasivam DO; Muralikrishnan, Radhakrishnan

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Indian Journal of Ophthalmology: Jul–Sep 2005 - Volume 53 - Issue 3 - p 173-176
doi: 10.4103/0301-4738.16675
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Abstract

In India, there are 12.5 million blind and it is estimated that 50% to 80%1,2 of them are blind due to cataract. In addition to the backlog, an additional 3.8 million become blind each year due to cataract.3 Most patients had advanced stages of cataract with intumescent, mature or hypermature lenses. Majority of these patients are socioeconomically backward and cannot afford procedures such as phacoemulsification. Conventionally, in the last millenium Extra Capsular Cataract Extraction with Posterior Chamber Intraocular Lens Implantation (ECCE-PCIOL) was considered an effective means of restoring visual function and improving vision related quality of life in developing countries. However, it has its own problems related to wound suturing with its associated complications and late visual rehabilitation.4 Recent reports indicate that both Manual Small Incision Cataract Surgery (MSICS) and ECCE-PCIOL are safe and effective for treatment of cataract surgery, however, MSICS gives better uncorrected vision.5 In this context, MSICS is gaining popularity in developing countries as an inexpensive alternative to phacoemulsification.6 Inspite of the fact that MSICS can be a cost-effective procedure, more research on the outcomes of MSICS is warranted.7 This study reports the results of a prospective observational study done to assess the safety and efficacy of MSICS in white cataracts with trypan blue assisted continuous curvilinear capsulorrhexis (CCC).

Patients and Methods

This study included 100 eyes of 100 consecutive patients with white cataracts who had routine MSICS operated at Aravind Eye Hospital, Pondicherry, between May and December 2003. The patients were operated at the charitable section of the hospital through either an outreach camp or direct availed services at free/subsidised cost. Preoperative examination like detailed slit lamp examination, schiotz tonometry, keratometry, A scan biometry and all routine pre-operative examinations were done at the base hospital (for camp patients after transportation), one day prior to surgery. White cataracts were classified as intumescent, mature or hypermature based on the depth of the anterior chamber, appearance of the anterior capsule and nature of lens matter pre-operatively. Cataract in eyes with shallow anterior chamber caused by hydrated swollen lens matter constituted intumescent group. A cataract with totally opaque lens matter and normal anterior chamber depth was considered mature. Hypermature cataracts had milky cortex or fibrous anterior capsule or both. The inclusion criteria included white cataracts with healthy endothelium (examined under high magnification using slit lamp) and without coexisting ocular pathology. Patient with small non-dilating pupil (< 5mm), pseudoexfoliation (examined by slit lamp) and diabetes (detected by routine urine sugar, if positive fasting blood sugar was done to confirm) were excluded from the study.

B scan ultrasonography was done only in eyes with abnormal pupillary reaction (relative afferent pupillary defect) with no perception of light.

Surgical technique

After an adequate mydriasis with tropicamide 0.8% and phenylephrine 5%, a combination of retrobulbar and facial block was administered. All surgeries were performed by a single surgeon (RV).

A superior rectus bridal suture was fixed. A fornix based conjunctival flap was created superiorly and haemostasis achieved with bipolar diathermy. A partial thickness 6 - 6.5mm frown shaped external scleral incision was made 2 mm behind the limbus. Scleral tunnel was constructed using a crescent knife (Sharpedge, India) and extended up to 1.0 mm into clear cornea. Additional paracentesis was made at 10'o clock position using a paracentesis knife (Sharpedge, India). Through the paracentesis, first an air bubble was injected to reform the anterior chamber and protect the endothelium, then 0.1 ml of 0.06% trypan blue (Auroblue, Aurolab, India) was injected below the air bubble using a 26 g needle. After a few seconds the air bubble was removed by injecting viscoelastic (Aurovisc, Aurolab, India) through the paracentesis to attain a uniform staining of the anterior capsule.

A 3.2mm keratome (Sharpedge, India), was used to access the anterior chamber and the internal corneal incision was extended for about 0.5mm more than the external scleral incision. The anterior chamber was deepened using a viscoelastic and a CCC of 5 - 6 mm was initiated and completed using a bent 26-gauge needle mounted on a viscoelastic syringe. In most of the cases of mature and intumescent cataract, CCC was completed with a cystitome. In cases of hypermature cataract, a small trap door or nick was made in the anterior capsule through which the liquid cortex was emptied and the CCC was completed using an utrata capsulorrhexis forceps. If the CCC margin extended to the periphery, the capsulotomy was converted to canopener type. Hydroprocedures were done with a 24-gauge hydrodissection cannula. The nucleus was made to rotate freely by hydroprocedures. A sinskey hook was used to hook out one pole of the nucleus outside the capsular bag and the rest of the nucleus was wheeled out into the anterior chamber.

After a good cover of viscoelastic, the prolapsed nucleus was extracted from the eye using an irrigating vectis (Indogerman, India) employing the principles of mechanical and hydrostatic pressure by pressing the posterior lip to open the valve for the exit of the nucleus. The cortex was washed using a simcoe cannula (Indogerman, India) and a 6 mm optic PMMA PCIOL (Aurolab, India) was implanted in the capsular bag inflated by viscoelastics. The viscoelastic material was replaced by a balanced salt solution and stromal hydration was performed by injecting fluid to the side of the paracentesis. The integrity of the self-sealing scleral incision was ensured and the cut conjunctival flap was apposed using a forceps fitted to bipolar diathermy.

Types of cataract, intraoperative findings or complications were recorded both in the case records as well as in a standard proforma. Postoperatively, patients were examined on the 1st and 40th post-operative days. A high follow-up rate on Day 40 was achieved with a strong post-operative counselling process in the hospital. The intraoperative and postoperative complications were graded according to Oxford Cataract Treatment and Evaluation Team (OCTET) classification8. According to OCTET, Grade I were trivial complications that may have needed medical therapy, but were not likely to result in a marked drop in visual acuity. Grade II were intermediate complications that needed medical therapy, and would have resulted in a marked drop in visual acuity if left untreated. Grade III were serious complications that would have needed immediate medical or surgical intervention to prevent gross visual loss.8 Uncorrected Visual Acuity (UCVA) and Best Correct Visual Acuity (BCVA) using a Snellen's chart were also recorded on the 1st and 40th postoperative days. On the 40th postoperative day, the complete ophthalmic examination included slit lamp examination, fundus examination and refraction.

Results

Intraoperative

Of the 100 eyes operated, 55 had surgery in the right eye and 45 had surgery in the left eye. There were 49 males and 51 females in the study. The pre-operative vision for all patients were either FCF (finger counting close to face) or HM (hand movements) or PL (perception of light). Surgery was done on 16 intumescent (16%), 67 mature (67%) and 17 hypermature (17%) cataracts (Table 1). Capsulorhexis tear was converted to can-opener type of capsulotomy in 4 cases (4%). All the four cases were intumescent and all of them developed intraoperative miosis. In the rest of the 96 eyes, CCC was completed successfully. One of the patients had inferior iridodialysis during delivery of a big nucleus. None of the eyes had posterior capsular rupture or zonular dialysis and no eyes were converted to conventional ECCE.

Table 1
Table 1:
Demographic characteristics of patients (N=100)

Postoperative

On the first postoperative day, according to OCTET classification, corneal oedema with Descemet's folds >10 developed in 6 eyes (6%), corneal oedema with Descemets folds < 10 developed in 7 eyes (7%). Mild iritis was seen in 6 eyes (6%) and moderate iritis with fibrin membrane was seen in 3 eyes (3%). Iridodialysis was observed in 1 eye (1%) and 96 eyes had PCIOL in the bag. An overall postoperative complication rate of 23% comprising those of varying degrees is reported (Table 2). All these complications were resolved before the patients were discharged. Patients without postoperative complications were discharged on the second postoperative day, and those with moderate iritis were discharged on the third postoperative day. On the 40th postoperative day, 99 patients (99%) had a BCVA of 6/18 or better of which 94% achieved a BCVA of 6/9 or better (Table 3). Categorising postoperative visual acuity as per the WHO Guidelines - good outcomes (6/6 - 6/18), borderline outcomes (< 6/18-6/60) and poor outcomes (< 6/60), none of the patients presented themselves under the Poor outcomes category. Considering UCVA on Day 40, 77 patients (77%) presented themselves under good outcomes against the 64 patients (64%) on Day 1.On Day 40, only one patient had UCVA of 3/60 due to Cystoid Macular Edema (CME). In case of BCVA, 99 patients (99%) on Day 40 against 94 patients (94%) on day 1 (Figure 1) had good visual outcome.

Table 2
Table 2:
Findings on the postoperative day 1 (n = 100)
Table 3
Table 3:
Postoperative Visual Acuity – Number of patients (95% CI)
Figure 1
Figure 1:
Postoperative visual outcome (WHO Guidelines)

Discussion

White cataracts constitute a significant volume of cataract surgical load in developing countries like India.9 Currently, satisfactory results have been published with respect to phacoemulsification in white cataracts.91011 In a developing nation like India, where cataract backlog is still a socioeconomic problem, procedures like phacoemulsification remain an expensive modality of management, and majority of the population find it difficult to afford it. MSICS promises to be a viable cost effective alternative in this regard.71213 The safety of this procedure in white cataracts is enhanced by the adjunctive use of trypan blue dye as in our study the success rate of CCC was 96%.

Jacob et al reports a failure of CCC with adjunct use of trypan blue in 3.85% of eyes with white cataract.11 This compares favourably with our results in four cases (4%). All those cataracts in which the CCC was converted to can-opener type were intumescent in nature. The incomplete CCC encountered was possibly due to increased intralenticular pressure. The challenge of performing CCC in white cataracts is well documented.10 This is because of lack of red reflex, poor contrast between the anterior capsule and the underlying cortex, high intralenticular pressure in intumescent cataracts, leaking of lens matter from the anterior capsule puncture sites and the occasional presence of capsular fibrosis. Various methods have been described to tackle such situations effectively. Use of trypan blue is found to be safe and effective in performing a CCC.14 In MSICS, it also helps in making the difficult step of nucleus prolapse through an intact capsulorrhexis safe and effortless, because the dye stained capsular rim is distinctly visible all throughout the surgery. As a result, any compromise to the capsular bag during prolapse of nucleus can be detected easily and relaxing incisions can be made at any point of the process thereby saving the intracapsular removal of nucleus.

Immediate postoperative complications such as corneal oedema found in 13% of the cases in our study were higher than the published results of phacoemulsification in white cataracts911 raising doubts whether phacoemulsification is more endothelial friendly. However, all of them were resolved with medical therapy by the time of discharge. One of the major reasons for the high incidence of corneal oedema in our situation is that many of the cataracts were hard and were camouflaged in white cortex and many of them had grade 5 cataract similar to what has been reported in the literature.10 In such circumstances, MSICS has been found to be effective to tackle these hard cataracts without much intraoperative complication, as demonstrated in our study (intraoperative miosis-4% and inferior iridodialysis-1%). Final visual outcome on the 40th postoperative day was satisfactory, with 94% of patients having BCVA of 6/9 or better. It compares favourably with other studies on white cataracts.91011 Jacob et al reports that 3.85% of cases where a CCC had failed it had to be converted to conventional ECCE.11 This was not the case with our study, as we could comfortably continue a sutureless procedure MSICS with a can-opener capsulotomy.

This study concludes that creating a complete CCC and prolapsing the nucleus from the bag into the anterior chamber are the two difficulties encountered during MSICS in eyes with white cataracts. Trypan blue staining helps the surgeon to visualise the anterior lens capsule while performing CCC. Secondly, it makes the prolapse of nucleus using sinskey hook a very safe maneuver by delineating the CCC margin and the underlying cortex. Hence, in developing countries like India where phacoemulsification may be unaffordable to the majority of population requiring cataract surgery, MSICS could to be a safe and efficacious alternative in white cataract, especially with the adjunctive use of trypan blue dye.

Proprietary or Financial Interest:

None

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Keywords:

Cataract; manual small incision cataract surgery; hypermature cataract; capsulorrhexis; trypan blue dye

© 2005 Indian Journal of Ophthalmology | Published by Wolters Kluwer – Medknow