Pre-operative minimal-cycloplegia mydriasis for capsulorrhexis in hypermature intumescent cataract

Introduction

Capsulorrhexis in hypermature intumescent cataract remains a challenge till today. Coventionally adrenergic-anticholinergic combination eye drops (e.g., phenylephrine-tropicamide) are used for pre-operative pupillary dilatation in cataract surgery. This achieves synergy in dilatation, but anticholinergic-induced cycloplegia makes already tense lens-capsule of intumescent cataract more taut, and completion of capsulorrhexis becomes difficult, often resulting in Argentanian flag sign, peripheral extension. An alternative mydriasis-without-cycloplegia strategy (phenylephrine) is also tried for better maintenance of mydriasis^[1] but it’s capsule-slackening effect was not thought of. However on technical side some techniques have evolved over the years to solve the problem. Gimbel et al. (1990)^[2] described a two-stage capsulorrhexis. First a small CCC is made, liquefied lens material is aspirated, then rhexis is secondarily enlarged. Bhatterjee et al. (1999)^[3] first created an anterior capsular opening with a needle and then the liquid material was intermittently aspirated until the lens capsule was decompressed. Then the endoillumination technique, as described by Mansour, was used to complete the capsulorrhexis. Richards et al. (2002)^[4] used Neodymium: YAG laser to create an anterior capsulotomy just prior to surgery. Hausmann (1991)^[5] used a bipolar diathermic capsulotome as an alternative to capsulorrhexis to create a round anterior capsulotomy. Femtosecond laser Capsulotomy,^[6] Nanopulse capsulotomy^[7] have been introduced recently. Rajan M et al^[8] used Punchorhexis- simultaneous puncture of the anterior capsule and decompression of the capsular bag done with phaco needle with burst phaco power. However none of the techniques could offer a gold standard, because these techniques are predominantly technology-dependent rather than science driven and requires high end costly instruments. In contrast, we exploited accommodation, a natural physiological phenomenon to solve the problem.

Cycloplegia during intumescent cataract surgery: A blessing or boon? The current practice is to use cycloplegic (Homatropin / Tropicamide/ Cyclopentolate) in pre-operative pupillary dilator regimen. However, cycloplegia makes capsule taut by increasing tension on zonules and thus makes capsule more prone to radial tear and run away. Therefore, Roy P^[9] developed a hypothesis of “minimal cycloplegic approach to dilatation” to facilitate favourable capsular behaviour during capsulorrhexis. As lens is in a relatively accommodated state in this approach, zonules remain relaxed, capsule flaccid and capsular behaviour is favourable rather than hostile.

Aims and Objectives

To study the relative ease and feasibility of capsulorrhexis in hypermature cataract surgery, with ocular instillation of an alternative regimen of a minimal cycloplegic tropicamide 0.25%, and 5% phenylephrine instilled in succession, compared to the standard practice of using the fixed-dose combination formulation of 0.8% tropicamide + 5% phenylephrine.

Materials and Methods

The study used a prospective observational 2-arm comparison design. The study commenced with due approval of Institutional Ethics Committee. Sixty-one (61) patients undergoing hypermature intumescent cataract surgery by standard MSICS+IOL technique and in whom either of the two regimens, MCM (‘Minimal-Cycloplegia Mydriasis’) or ‘Standard FDC’ were used for pupillary dilatation, were observed.  Outcome analysis was done by Fisher’s Exact Test.

All surgeries were done by a single surgeon. Routine pre-operative assessment done in each case with USG of posterior segment to rule out posterior segment pathology. Pre-operatively after taking proper informed consent, the patients were randomly assigned to one of the 2 groups as follows:

Results

Data are entered in excel sheet and analysis of results were done.

The age and sex distribution of the patients of the study was as follows [Table 1], [Table 2].

Outcome measure of the study was as follows: Pupillary dilatation ([Table 3]), Ease of Rhexis ([Table 4]), Attainment of BCVA >/= 0.5 at 6^th post- operative week ([Table 5]), and Freedom from complications ([Table 6], [Table 7]).

The BCVA of >/= 0.5 at 6^th post-operative week is higher in Minimal Cycloplegia Mydriasis (24/29 i.e. 82.75%) than that in Fixed dose combination (FDC) mydriasis (11/32 i.e. 32.37%). This difference is highly statistically significant by Fisher’s Exact Test (P =0. 0002). ([Table 5])

The chance of anterior chamber reaction (cells >/=3+) in the 1^st post-operative day is significantly higher in the Minimal Cycloplegia Mydriasis (MCM) than that in the Fixed dose combination (FDC) mydriasis. This difference is statistically significant.(Fisher’s Exact Test, P = 0.0086) ([Table 6])

However, in both Alternative Minimal Cycloplegia Mydriasis (MCM) and Standard Fixed dose combination (FDC) mydriasis, the A/C reaction is transient and cleared by1st post-operative week (P = 1.0000).

Discussion

Capsulorrhexis by “Minimal-Cycloplegia Mydriasis Approach” was first time reported by the author (PR) of this communication and preliminary reports of this study was displayed In: American Society of Cataract and Refractive Surgeons Annual Conference, San Diego 2019, Scientific Film section^[9] and presented in All India Ophthalmological Society Annual Conference, Indore 2019, in Free Paper section. No other report on this approach can be found in literature till date.

Capsulotomy/Capsulorrhexis in hypermature cataract: it is an established fact that the seat of presbyopia lies is in the lens substance and not on the capsule. Therefore, lens-capsule reacts to accommodative effort even in presbyopic age. Development of in-the-bag presbyopic IOL speaks volumes for it.

In hypermature intumescent cataract capsule is more fragile in addition to impaired visibility of red reflex. Leakage of liquefied cortical matter and rhexis-tears can extend to the periphery due to high intra-lenticular pressure with sudden capsulorrhexis radialization.

In hypermature white cataract, besides staining the anterior capsule to increase its visibility, creation of a small capsulorrhexis which is secondarily enlarged after aspirating the liquefied milky lens contents can be attempted. Gimbel et al.^[2] evaluated two techniques of capsulorrhexis for hypermature intumescent cataract: traditional one-stage capsulorrhexis and two-stage capsulorrhexis. They concluded that 2-stage rhexis helps prevent sudden radialization of capsulorrhexis and other intraoperative complications.

Femto-second laser assisted^[7] anterior capsulotomy/capsulorrhexis is said to be of special utility in hypermature intumescent cataract, being accurate, circular and centered, thus avoiding IOL eccentricity and tilt caused by asymmetric capsular bag cntraction. Two-step femto-second laser assisted technique for hypermature intumescent cataract has been described with better 360˚ overlap of optic and implant stabilization.

Radio-frequency diathermy^[5] has also been successfully used to perform capsulorrhexis in hypermature intumescent cataract with varied results.

Different techniques of capsulorrhexis/capsulotomy have undergone progressive evolution to achieve perfection in size, shape, centration and overlap. Besides they also possess various disadvantages which have already been mentioned e.g. in laser assisted techniques higher costs are the major limiting factor. While manual CCC remains the gold standard and most commonly utilized technique of anterior capsulorrhexis, our study aims at improving this procedure in terms of ease and feasibility by pharmacomodulation of drugs used pre-operatively particularly in cases of hypermature white cataract for good visual and anatomical outcomes. Besides this technique can be utilized for all patients even with poor financial conditions due to its low cost as compared with the laser assisted techniques.

The possible explanation of increased anterior chamber reaction in 1^st post-operative day might be due to minimization of cycloplgic might cause micro twitching of iris resulting in dispersion of iris pigments. Our finding corroborates with findings of Iftikhar M et al (2021)^[1] who mentioned in their review article about increased incidence of  Iris-related complications (11 out of 30 eyes) in intracameral use of Phenylephrine without use of any cycloplegic.

Therefore, the technique used in our study merits consideration for use in hypermature white cataract patients.

Conclusion

This is the first time in literature that the challenge of capsulorrhexis in hypermature intumescent cataract was addressed by pharmacomodulation of preoperative pupillary dilatation.

In “Mnimal Cycloplegia Mydriasis” (MCM) approach, good pupillary dilatation compatible with performance of all steps of surgery was achieved.

In “Mnimal Cycloplegia Mydriasis” (MCM) approach, the outcome of hypermature intumescent cataract surgery was much better in term of Ease of rhexis and attainment of BCVA of 6/12 or more.

“Mnimal Cycloplegia Mydriasis” (MCM) approach might cause increased anterior chamber reaction in 1^st post-operative day. But the reaction is transient and went off completely in all cases by 1^st week.

Recommendation

Therefore, the “Mnimal Cycloplegia Mydriasis” (MCM) technique used in our study merits consideration for use in hypermature cataract surgery.

Source of Funding

None.

Conflict of Interest

None.