We would like to extend our heartiest congratulations to Pandav et al 1 for their study "Long-term outcome of Ahmed glaucoma valve implantation in eyes with intractably raised intraocular pressure following pars plana vitrectomy." The study is very informative; however, we would like to raise a few points regarding it.Pandav and colleagues have concluded that the mean intraocular pressure (IOP) was significantly reduced from the baseline value (P < 0.0001) at all the follow-up visits, along with a significant reduction in the number of antiglaucoma medications. However, in the study, 11 of the 78 patients had undergone previous interventions such as trabeculectomy and diode laser cyclophotocoagulation before Ahmed glaucoma valve (AGV) implan-
Purpose: To study and document electron microscopic features in explanted hydrophobic microvacuoles affected acrylic intraocular lenses (IOL) which were in vivo for an average duration of 11 years. Methods: Scanning electron microscopic (SEM; Hitachi S 3000 N EXAX Genesis VP SEM) study of five explanted hydrophobic acrylic IOL which had clinically evident microvacuoles prior to explantation, was done. The IOLs were in vivo for a prolonged period and needed explantation for various indications. Only those hydrophobic acrylic IOLs which fulfilled the inclusion criteria were included. The findings were compared with control specimens. Results: The IOLs were in vivo for an average duration of 11.6 ± 4.21 years. The cause of explantation of IOL was subluxation in four cases and low visual acuity in one case. Bulk degradation and microvacuoles on cut sections throughout the IOL optics and undulating surface patterns over both the surfaces of the IOL has been documented in all the specimens. No such findings were noted in the control specimens where the surface and texture were homogenous. Conclusion: SEM findings of the structural changes in explanted IOL documented in the study demonstrate that hydrophobic acrylic IOL is degradable in vivo . Microvacuoles are a clinical manifestation of the structural changes that occur at a microscopic and molecular level. These changes are not seen in IOLs which have not undergone intraocular implantation. To our knowledge, a similar study of this kind has not been done.
Purpose: The aim of this study was to report scanning electron microscopic (SEM) and energy dispersive spectroscopic (EDS) findings of three specimens of opaque hydrophobic acrylic intraocular lens (IOL) explanted in delayed postoperative period for visual indications. Methods: Clinical data and photographs from each subject were obtained. Explanted IOLs were examined under gross and light microscopy followed by SEM coupled with EDS. Results: All three subjects underwent IOL implantation following senile cataract extraction at an average age of 64.3 ± 0.3 years, and the IOLs were in situ for a duration of 11.3 ± 4.04 years. The IOL explantation and exchange were done due to late postoperative opacification of the IOL and significant visual deterioration. The milky iridescent opacity affected the full thickness of IOL optics in the first two specimens and in the third only two surfaces were involved. SEM detected surface cracks in the first specimen, typical conglumated surface, pores and accumulation of crystals with surface deposit of nano-particles on the second specimen and uneven surface erosion in the third specimen. SEM detected mainly sodium (Na) and chloride (Cl) spikes. All patients recovered normal vision following IOL exchange. Conclusion: SEM features of the IOL optics and absence of calcium and phosphate spikes in EDS and other findings were consistent and suggestive of hydrolytic biodegradation of hydrophobic acrylic IOL polymer in ocular media and was responsible for delayed postoperative opacification of the hydrophobic IOLs and visual loss.
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