Eyeworld

63 EW RESIDENTS November 2018 the smaller 2.20 mm incision was associated with increased rate of traumatic DMDs, linking that result to slower healing times. They go on to hypothesize that the "rela- tive tightness" of the lens cartridge within the smaller wounds results in more wound stretch. Impressively, they went on to consider the planar circumference of the ellipsoid lens cartridge and determine that the fully dilated 2.20 mm incision pos- sesses a circumference 0.81 mm less than that of the cartridge, resulting in wound stretch. The authors presented consid- erations regarding the impact of the different phacoemulsification tips utilized in the different size incisions, defending the selection of each tip being certified for incisions significantly smaller than the study incisions. Rather than measure "tightness" of the incisions around each phacoemulsification tip, the authors suggest using incision size as surrogate marker. Given the differ- ent corneal thickness and stiffness characteristics of each operated cor- nea, it may have been preferable to measure tightness with an appropri- ately sized instrument. This would have been particularly helpful given that the authors go on to suggest that mechanical stretching of the wound is a component of the poor wound healing observed with the smaller incisions. Noting that the smaller 2.20 mm incision resulted in increased endothelial dysfunction with polymegathism, the authors specu- lated that perhaps the varying flu- idics of the different phacoemulsi- fication tips were the culprit. While they cite that "fluid flow through a cylindrical phacoemulsification tip is exponentially proportional to the inverse diameter of the tip," they did not measure or demonstrate either an increased rate of flow or increased turbulence. Actual exper- imental demonstration of increased flow, turbulence, or untoward effect on endothelium would have been preferable. The authors next considered the merits and complications of wound hydration in uniplanar incisions. The authors reference that some of the main incisions and some of the paracenteses required wound hydra- Posterior incision recession (PIR) was found to increase from 1 week to 3 months equally in each group. This PIR is consistent with what has been previously demonstrated by other investigators looking at corneal wound healing and scar revision. 2 Endothelial polymegathism (while not statistically different at baseline; 29.5% [2.20 mm] and 28.3% [2.85 mm] [P=0.07]) was significantly increased in the 2.20 mm group at 1 week and 1 month (P=0.02 and P<0.01). However, the differences resolved by 3 months. There was no difference found in pleomorphism between groups, and both groups demonstrated an expected decrease in ECD from baseline at 3 months without an intergroup difference. The authors demonstrate that the incision width measured postoper- atively by AS-OCT is smaller in the 2.20 mm incision group at all fol- low-up times as would be expected. Finally, the authors compared the incision characteristics by measuring the angle between the incision and the tangent of the corneal epithelial surface at the incision entry point and the incision size at follow-up. They found the main incision angle to be smaller than the paracentesis incision angle (25.03 degrees vs. 36.62 degrees) regardless of initial incision size, suggesting that this smaller angle aides in preventing incision leak- age. They report that a single main incision (with a larger angle, 35 de- grees) and all paracentesis incisions leaked initially and required stromal hydration potentially contributing to prolonged recovery. Compar- ing incision sizes at follow-up, the authors reported that the incision length was not different at any time point regardless of initial incision size. The larger 2.85 mm incisions had correspondingly larger incision widths at all time points relative to the 2.20 mm incisions. Both groups had a reduction in incision length and width from day 1 to month 1 without any change beyond this point. Discussion In this study, the authors compared uniplanar clear corneal incisions of two sizes (either 2.20 mm or 2.85 mm), and they reported that tion to seal. Without notation about how many wounds were hydrated to seal, it is unclear to what degree this confounding factor influenced the results. In spite of these few, small missed opportunities for more precise measurement and data collection with regard to "wound tightness" evaluation, the authors present a compelling paper for con- sideration against the general trend to reduce incision size in ocular sur- gery. By demonstrating an increased rate of DMD and slower wound healing with the smaller 2.20 mm incision, they provide a rationale for practicing surgeons to continue utilizing the larger 2.85 mm clear corneal incisions, particularly in patients who are prone to corneal endothelial damage. EW References 1. Davison JA, Chylack LT. Clinical application of the lens opacities classification system III in the performance of phacoemulsification. J Cataract Refract Surg. 2003;29:138–45. 2. Wang L, et al. Healing changes in clear corneal cataract incisions evaluated using Fourier-domain optical coherence tomography. J Cataract Refract Surg. 2012;38:660–5. Contact information Wayman: laura.l.wayman@vanderbilt.edu incisions: could tighter incisions delay recovery? 2.85 mm incisions" OCT analysis of phacoemulsification incisions: could tighter incisions delay recovery? A prospective randomized trial of 2.2 mm versus 2.85 mm incisions Sunny Li, BMedSc(Hons), Stuti Misra, BOptom, PhD, Henry Wallace, BMedSc(Hons), James McKelvie, MBChB, PhD J Cataract Refract Surg. 2018;44(11):1333–1335. Purpose: To characterize the effect of incision size on corneal incision repair and remodeling over 3 months following cataract surgery. Setting: Department of Ophthalmology, Auckland District Health Board, New Zealand Design: Prospective double-masked randomized study Methods: One hundred eyes of 100 patients undergoing routine cataract surgery were randomized to receive uniplanar clear corneal incisions of 2.20 mm or 2.85 mm. Anterior segment optical coherence tomography (AS-OCT) and specular microscopy were completed at baseline and day 1, 7, 30, and 90 following surgery. Incision thickness, length, width, gaping, and angle were analyzed using AS-OCT. Endothelial cell density (ECD), polymegathism, and pleomorphism were assessed using specular microscopy. Results: Of 100 recruited patients, 50 were allocated to each incision group. Ninety-nine patients (99%) attended all assessments. Incisions of 2.20 mm were associated with over 50% more Descemet's membrane detachments (DMD, P=0.01). Patients with DMDs demonstrated increased endothelial wound gaping, slower visual recovery, and increased corneal thickness at the incision site at all visits (φ=0.54, P<0.01). The 2.20 mm incision group demonstrated greater polymegathism despite no difference in phacoemulsification energy between treatment groups (2.20 mm=32.3±6.2%; 2.85 mm=30.8±6.5%, P=0.02). At day 90 following surgery, 2.20 mm incisions demonstrated lower ECD (2195±360 cells/mm 2 ) than the 2.85 mm group (2397±335 cells/mm 2 , P=0.01). Final visual acuity, gaping, and angles was not significantly different between the incision groups. Conclusions: Corneal incisions with a width of 2.2 mm are more prone to trauma than 2.85 mm incisions during routine cataract surgery. Corneal incisions with signs of trauma are associated with prolonged visual recovery and slower healing following surgery.

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