Postoperative tamponade with perfluoro-n-octane may decrease the rate of redetachment in giant retinal tear repair compared with silicone oil or perfluorocarbon gas alone. We found no adverse effects directly attributable to perfluoro-n-octane.

Key words: Contact lens, corneal topography, keratoconus, unilateral keratoconus. Purpose:To determine the incidence of true unilateral keratoconus on the basis of cornputerised corneal topography in a group with clinically diagnosed unilateral keratoconus. Methods:Retrospective review of 295 patients with keratoconus identified 51 patients with a provisional diagnosis of unilateral keratoconus. Thirty-one of these patients were re-examined clinically and 21 patients met the criteria for a clinical diagnosis of unilateral keratoconus. Computerised corneal topographic analysis (Tomey TMS) was then performed.

Objective:To present the clinical spectrum of lamellar macular defects and describe the different subtypes based on their optical coherence tomography (OCT) configuration and visual prognosis.Methods:The retrospective observational case series reviewed OCT scans of 92 eyes with lamellar macular defects. Lamellar macular defects were categorised into subtypes of macular pseudohole (MPH), lamellar macular hole (LMH) and foveal pseudocyst (FP) according to their OCT morphology. The defects were quantitatively characterised in terms of base diameter, depth and central foveal thickness, and examined for the presence of associated epiretinal membranes (ERM).Results:Visual acuity (VA) was significantly correlated with the central foveal thickness and depth of the lamellar defect. MPH was associated with better VA compared with LMH and FP. MPH was of a smaller base diameter and had a greater central foveal thickness than that of LMH and FP. Fifty-per cent of all lamellar defects had an associated ERM.Conclusions:Different profiles of lamellar macular defects were characterised and quantified by OCT. Deeper and wider lamellar defects were associated with poorer visual outcome. Such objective parameters lamellar macular defects are of value when explaining to patients regarding their decreased acuity. Future prospective investigations are required to study the natural history of lamellar defects of different aetiology and surgical indications.