Abstract
Abstract: :
Purpose: Based on the post–surgical changes following standard 20–gauge Pars Plana Vitrectomy (PPV) including astigmatism, inflammation, and changes in the ocular surface, we hypothesized that the postoperative recovery of visual acuity (VA) is faster after 25–gauge Transconjunctival Sutureless Vitrectomy (TSV) as compared to conventional PPV. Methods: In order to isolate the effect of surgical technique on visual acuity, we performed a retrospective case– control study of patients who underwent TSV or PPV for Epiretinal Membrane (ERM) by a single surgeon (LC). The choice of a relatively simple procedure such as ERM peel served to limit confounding by variables such as operating times, presence of media opacities, and efficacy of each surgical technique. Best Corrected Snellen VA data were recorded from the chart at 3 points: 1) preop VA on the last visit prior to surgery, 2) Postop Day (POD) #1 VA, and 3) Postop Visit (POV) #2 (POD #7–18) visual acuity. Statistical analyses were based on the chi–square distribution. Results: There were 12 patients who underwent TSV/MP for ERM (Mean Age=68; Male:Female=1:1; Median preop VA=20/70). A comparable control group included 10 patients who underwent PPV/MP for ERM (Mean Age=67; Male:Female=1:1; Median preop VA=20/80). The average change in the number of Snellen lines on POD #1 was –2.8, and –3.2 for the TSV/MP and PPV/MP groups respectively. This average on POV #2 was –1.6 lines for both groups. While the overall change in visual acuity was similar in the two groups, further analysis revealed that on POD#1, almost all patients (90%) in the PPV group had a decrease in vision, compared to a significantly fewer percentage (75%) in the TSV group (p=0.05). By POV #2, however, the percentage of patients with a decrease in vision was similar in both groups (58% vs. 60%, TSV/MP vs. PPV/MP; p=0.52). Since VA less than 20/400 was difficult to quantify, a subgroup analysis was performed for patients with preoperative visual acuities greater than 20/200. Among these patients, on POD#1 30% (3/10) had VA greater than 20/200 in the TSV/MP group vs. 14% (1/7) in the standard PPV/MP group (p=0.04). By POV #2, the ratios were 70% (7/10) in the TSV/MP and 57% (4/7) in the standard PPV/MP groups (p=0.13). Conclusions: Though the final visual outcomes following TSV and PPV may be similar, TSV is more likely to lead to faster visual acuity recovery in the immediate postoperative period compared to PPV, and this may be especially true of patients who have a higher preoperative visual acuity.
Keywords: vitreoretinal surgery • visual acuity • clinical (human) or epidemiologic studies: systems/equipment/techniques