Corneal thickness and morphology after orthokeratology of six-month lens wear among young Malay adults

@#Background: Menicon Z night orthokeratology (OK) lenses was introduced in Malaysia in 2015 and to date there is no report on its effects on the cornea. The objective of this study was to examine short term changes in corneal thickness and morphology of endothelial cells in young Malay adults after wearing Menicon Z night OK lenses. Methods: Corneal thickness was measured at the central and mid-peripheral locations of 20 participants aged 22.45±1.19 years using Tomey SP-3000 A-scan ultrasonography. Endothelial images of the central and peripheral locations captured using Tomey EM-3000 specular microscope were noted. Corneal thickness, endothelial cell density (ECD), coefficient of variation in cell size (CV), and hexagonality (HEX) at baseline, 24 hours, three months and six months after treatment were noted and analysed using repeated measure analysis of variance. Results: Central corneal thickness decreased significantly over a three-month period (p=0.001) and stabilised thereafter. There were no significant changes in thickness in all peripheral areas measured (p>0.05), and in ECD, CV and HEX after the six-month period (p>0.05). Conclusions: The current study showed that significant thinning of central cornea and none at the mid-periphery. OK lens wear with Menicon Z night lenses had no effects on corneal morphology over the six month period.

Quantitative & qualitative analysis of endothelial cells of donor cornea before & after penetrating keratoplasty in different pathological conditions.

Background & objectives: Endothelial cells of the donor cornea are known to be affected quantitatively and qualitatively in different pathological conditions after penetrating keratoplasty (PK) and this has direct effect on the clarity of vision obtained after PK. This study was undertaken to analyze the qualitative and quantitative changes in donor endothelial cells before and after PK in different pathological conditions. Methods: A prospective investigational analysis of 100 consecutive donor corneas used for penetrating keratoplasty between June 2006 and June 2008, was conducted. The patients were evaluated on the first day, at the end of first week, first month, third and six months and one year. Results: A decrease was observed in endothelial cell count in all pathological conditions. After one year of follow up the loss was 33.1 per cent in corneal opacity, 45.9 per cent in acute infective keratitis (AIK), 58.5 per cent in regrafts, 28.5 per cent in pseudophakic bullous keratopathy (PBK), 37 per cent in descemetocele, 27 per cent in keratoconus and 35.5 per cent in aphakic bullous keratopathy (ABK) cases. Interpretation & conclusions: The endothelial cell loss was highest in regraft cases which was significant (P<0.05), while the least endothelial cell loss was seen in keratoconus cases. The cell loss was associated with increase in coefficient of variation (CV), i.e. polymegathism and pleomorphism. Inspite of this polymegathism and pleomorphism, the clarity of the graft was maintained.

Corneal Endothelial Morphometric Changes after Laser in Situ Keratomileusis with Residual Thickness less than 250 micro meter

PURPOSE: To evaluate endothelial cell changes following LASIK with residual corneal thickness of less than 250 micro meter. METHOD: We performed noncontact specular microscopy preoperatively, and 1 week, 1, 3, 6, 9 months after surgery to examine 82 eyes which had undergone LASIK. Corneal endothelial density (CD), coefficient of variation of the cell area (CV), and the percentage of hexagonal cells(hexagonality, 6A) were obtained according to the corneal endothelial cell analysis program. Analysis was done according to the parameters such as residual stromal bed thickness, number of laser pulse and percentage of ablated stromal thickness and preoperative spherical equivalent. RESULTS: Changes in CD and CV showed no significant difference throughout the follow-up period after surgery. Hexagonality, however, decreased after surgery. In particular, corneas with residual thickness of less than 235 micro meter or the number of laser pulse over than 400, or ablation more than 30% of stromal thickness showed significant decrease in hexagonality. CONCLUSIONS: This results suggest that LASIK with deep ablation might cause corneal endothelial damages, and at least 235 micro meter or more of residual thickness should be preserved to avoid endothelial damages.