Objective: To determine the effect of 23-gauge pars plana vitrectomy on corneal dioptric power through a comparison of difference in pre- and post- surgery keratometry.
Study Design: Prospective non-comparative interventional type.
Place and Duration of Study: The study was conducted at the Armed Forces Institute of Ophthalmology (AFIO) Rawalpindi from Dec 2016 to Jul 2017.
Material and Methods: We studied 33 patients (33 eyes) who underwent 23-gauge vitrectomy with mean age of 46.4 ± 12.8 years. Among them 13 were females and 20 were males. These patients were divided in four groups on the basis of pre-surgical diagnosis. 18 (55%) patients had rhegmatogenous retinal detachment, 9 (27%) had macular holes 3 (9%) with Vitreous hemorrhage and last 3 (9%) had dislocation of intraocular lens. Total vitrectomy was performed in all patients by standard 23G pars plana vitrectomy (PPV) procedure as used with three
scleratomies and tunnel shaped incision. Keratometry readings before the surgery and at the end of 1st, 6th and 12th post procedural weeks were recorded in horizontal (K1) and vertical meridian (K2) by utilizing topcon auto kerato-refractometer.
Results: The pre-operative dioptric power of cornea in horizontal and vertical meridian (K1 and K2 respectively) was statistically compared with post- operative dioptric power of cornea at the end of 1st, 6th and 12th postopertive weeks. At the end of first post- operative week there was significant difference between pre and post-operative corneal dioptric power with horizontal p-value<0.05 and vertical <0.04; leading to astigmatism. However, at the end of 6th and 12th post procedural weeks there was no significant difference between pre and post-operative corneal dioptric power which is evident with insignificant p-values. The p-value at the end of 6th
post-operative week was 0.521 and 0.57 for K1 and K2 respectively. At the end of 12th post procedural week these values are 0.854 and 0.941 for K1 and K2 respectively. Clinically these patients did not have any sign or symptoms of astigmatism.
Conclusion: 23G was found safe procedure in vitreoretinal surgery with no insignificant change in corneal dioptric power except in cases in which silicone oil was used. However, due to small study group and short follow up further studies with longer follow-ups are required to establish the long-term changes in corneal dioptric power after 23G suture less vitrectomy.
Keywords : Astigmatism, Dioptric power, Keratometry, Pars plana vitrectomy, Suture less,