The incidence of corneal abnormalities in the Silicone Study. Silicone Study Report 7
G. W. Abrams, S. P. Azen, C. C. Barr, M. Y. Lai, W. L. Hutton, M. T. Trese, A. Irvine and S. J. Ryan
Kresge Eye Center, Wayne State University, Detroit, Mich, USA.
OBJECTIVE: To determine factors that were prognostic of corneal
abnormalities in eyes following surgery for severe proliferative
vitreoretinopathy. DESIGN: Subgroup analysis of the Silicone Study.
SETTINGS: Community and university-based ophthalmology clinics. MATERIALS:
Eyes with attached maculae at the 24-month follow-up examination that did
not have a pre-existing corneal abnormality. INTERVENTIONS: Vitrectomy
surgery with long-acting gas or silicone oil. OUTCOME MEASURES: Epithelial
and/or stromal edema, corneal opacity and/or previous corneal transplant.
RESULTS: The incidence of corneal abnormalities at 24 months was 27% and
did not differ significantly between treatment groups. Prognostic factors
were preoperative aphakia or pseudophakia (P = .003), preoperative iris
neovascularization (P = .006), reoperation (P = .001), the absence of a
fluid/gas exchange (P = .03), corneal touch by silicone oil (P = .02), and
the presence of aqueous cells (P = .009) or aqueous flare (P = .08). In a
multivariate analysis, independent prognostic factors were iris
neovascularization (relative risk [RR] = 13.1), aphakia or pseudophakia (RR
= 3.0), postoperative aqueous flare (RR = 5.4), and reoperations (RR =
3.4). Corneal abnormalities were correlated with poor visual acuity and
hypotony (P < .001). CONCLUSIONS: To our knowledge, this is the first
study to document that the incidence rates of corneal abnormalities are
equivalent between oil and gas. The incidence of corneal abnormalities in
gas-filled eyes was higher than expected, and remained high in oil-filled
eyes, despite the use of an inferior iridectomy. Successful surgical repair
of the retinal detachment with a single operation, and prevention and early
management of corneal touch by silicone oil should help to prevent corneal
abnormalities. If rubeosis iridis or severe aqueous flare is present,
preoperative treatment with intense topical and possibly periocular
steroids might reduce inflammation, which might mediate corneal damage.
