Purpose To assess variability in the coefficient of variation (COV) in cell area estimates when using different numbers of cells for endothelial morphometry. Methods Using non-contact specular microscopy images of the corneal endothelium, 4 sets of 20 cases were selected that included 200 cells and had overall (global) COV values of less than 30 (group 1), 31-40 (group 2), 41-50 (group 3) and over 50% (group 4). Subjects could be normal, or had ophthalmic disease (such as diabetes), a history of rigid or soft contact lens wear or were assessed after cataract surgery. A stepwise analysis was undertaken, 20 cells at a time, of the variability in cell area estimates when using different numbers of cells for the calculations. Results Variability in the average cell area values was higher if only 20-60 cells were used in the calculations and then tended to decrease. The standard deviation values on these average cell area values and the calculated COV showed the same overall trends and were more than twice as large for endothelia with marked polymegethism. Using more than 100 cells/ image in markedly polymegethous endothelia only increased the variability in the calculations.Conclusions These analyses indicate that substantial region variability in cell area values can be expected in polymegethous endothelia. The analysis further confirm that using only small numbers of cells (e.g. less than 50/image) in such cases is likely to yield far less reliable estimates of COV.

Purpose Assessment of the anterior segment by Orbscan in hyperopic eyes. Methods 30 normal right eyes (10 younger hyperopes, 10 older hyperopes, 10 younger emmetropes) were assessed with Orbscan II. Anterior chamber depth (ACD), horizontal corneal diameter (HCD), anterior (AK) and posterior corneal radius (PK), central (CCT) and peripheral corneal thickness (PCT, 4mm from centre) were analysed in the younger (≤ 45 years of age) and older hyperopic subjects (> 45 years). The data from the younger hyperopic group were also compared with the age‐matched emmetropic subjects. Results All data were normally distributed (p ≥ 0.403). For the 20 hyperopic subjects, the mean refractive error was +2.33 D (SD+/‐ 1.85 D), the mean ACD was 2.59 +/‐ 0.35 mm, with a mean HCD of 11.76 +/‐ 0.33 mm. The mean ACD was less in young hyperopes than in emmetropes (2.72 mm vs 2.91 mm). ACD was a further 10 % shallower in older hyperopes when compared to younger hyperopes, with the peripheral cornea also being slightly thinner (by about 4 %). No substantial differences between the younger and the older hyperopes were noted in HCD, PK, and CCT (p ≥ 0.094, independent samples t‐test), but younger hyperopes had on average a larger AK than older subjects, the difference being only just significant (p = 0.02). Conclusion These pilot studies indicate that most anterior segment biometrics are not substantially different between younger and older subjects with hyperopia. However, younger subjects had a slightly flatter anterior corneal radius and a thicker peripheral cornea, along with the expected (on average) lower ACD in hyperopic eyes and older subjects. Further studies are needed for refractive surgery procedures in older hyperopic patients.