First Author: P.Tranos GREECE
Co Author(s): M. Triantafylla A. Vakalis S. Asteriadis N. Kozeis
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To investigate the accuracy of preoperative biometry in eyes undergoing combined phacovitrectomy and to compare it with eyes having cataract surgery at a separate time point following vitrectomy. We also evaluated factors influencing refractive outcomes in the study groups.
''Ophthalmica'' Institute of Ophthalmology and Microsurgery, Thessaloniki, Greece
The files of patients with epiretinal membrane or macular hole who underwent combined phacovitrectomy (group 1) or phacoemulsification after pars plana vitrectomy (group 2) were retrospectively reviewed. Primary outcome measure was the intraocular lens (IOL) power prediction error (PE) and the percentage of eyes with PE>0.5D in the two groups. Secondary outcome measures were the correlation between epidemiological, clinical or surgical factors and dioptric shift. In addition, the influence of optical coherence topography (OCT) characteristics including the integrity of external limiting membrane (ELM) and elipsoid layer to the refractive error was investigated.
Seventy three eyes of 69 consecutive patients were identified and included in the study. The mean PE was -0.2D (range +1.4 to -2.5D) in group 1 and 0D (range +1.0 to -1.45D) in group 2. Dioptric shift greater than 0.5D was observed in 47% of eyes in group 1 as opposed to 17% of eyes in group 2 (p=0.027). The aforementioned refractive error was associated with worse baseline and final best corrected visual acuity (p=0.046 and p=0.021 respectively) and shallower anterior chamber depth (p=0.048). Elipsoid or ELM disruption was not associated with significantly greater postoperative refractive deviations (p>0.05).
Combined phacovitrectomy results in greater postoperative refractive error compared to phacoemulsification alone following vitrectomy. The myopic overcorrection frequently seen after combined surgery could be counteracted by aiming for residual hypermetropia. Patients with worse vision and shallow anterior chamber require more caution since they are prone to inaccurate preoperative biometry.