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A.A. Macedo, R. Madhok, V.C. Edwards, L.A. Polikoff, A.J. Taglienti, J.B. Serle; The Effect of Cataract Extraction and Intraocular Lens Placement on Optic Disc Topographic Measurements . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2551.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the effects of cataract extraction with intraocular lens placement on HRT parameters in the glaucomatous optic disc. Methods: Retrospective analysis of 29 glaucoma and ocular hypertensive patients using HRT and Humphrey Visual Field (HVF) studies from before and after cataract extraction and PC IOL. Patients had had at least two HRTs and two HFAs, one of each being less than 1.5 years before cataract extraction, and the others being 4 weeks to 1.5 years after cataract extraction. Exclusion criteria were: severe myopia (>–6 diopters), severe hyperopia (>+4 diopters), optic disc abnormalities (i.e. tilted disc, drusen), gross ocular abnormalities (i.e. retinal detachments, severe corneal opacities or other neurological or ocular abnormality producing nonglaucomatous visual field defects), and poor quality of the HRT (SD>50) and HVF (false positives, false negatives, and fixation losses > 25%) examinations. Pre– and post–op HRTs were compared for changes in the Moorfields Regression Analysis classification globally and in six sectors of the optic disc, as were differences in the 14 variables of the Multivariate Discriminant Analysis. Pre– and post–op HVFs were compared for differences in mean deviation and pattern standard deviation. Results: Significant increases in the HRT parameters mean (p=0.007) and maximum cup depth (p=0.048) were detected post–operatively, globally, and in all of the temporal sectors, except for the maximum cup depth of the temporal–superior sector. Standard deviation was 41% lower (p=0.001) and contour line modulation and maximum contour elevation were 51% higher (p=0.02, p=0.003 respectively) post–operatively. Rim volume increased in the temporal–superior and nasal inferior sectors (p<0.05). Mean RNFL thickness, and RNFL cross sectional area were both increased by 25% in the temporal–inferior sector (p=0.03). Analysis of the HVFs showed a decrease in mean deviation (1.51 db, p=0.0001), without accompanying changes in PSD or CPSD. Intraocular pressure was decreased 21% (p=0.0004) from pre–operative 17.4 +6.3 mmHg (mean + SD) to 13.7 +3.9 mmHg, following cataract surgery. Conclusions: This study suggests that cataracts may interfere with scanning laser tomography as performed by HRT. Alternatively, reductions in IOP observed in these patients may be another explanation for the changes noted post–operatively on HRT. These findings suggest a new baseline image should be obtained after cataract surgery in order to properly monitor glaucomatous progression.
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