Background: The interaction of the non-deletional α+-thalassaemia mutations Haemoglobin Constant Spring and Haemoglobin Quong Sze with the Southeast Asian double α-globin gene deletion results in non-deletional Haemoglobin H disease. Accurate detection of non-deletional Haemoglobin H disease, which is associated with severe phenotypes, is necessary as these mutations have been confirmed in the Malaysian population. Methods: DNA from two families with Haemoglobin H disease was extracted from EDTAanticoagulated whole blood and subjected to molecular analysis for α-thalassaemia. A duplex polymerase chain reaction was used to detect the Southeast Asian α-globin gene deletion. Polymerase chain reaction-restriction fragment length polymorphism analysis was then carried out to determine the presence of Haemoglobin Constant Spring and Haemoglobin Quong Sze. A combine- amplification refractory mutation system protocol was optimised and implemented for the rapid and specific molecular characterisation of Haemoglobin Constant Spring and Haemoglobin Quong Sze in a single polymerase chain reaction. Results and Conclusions: The combine- amplification refractory mutation system for Haemoglobin Constant Spring and Haemoglobin Quong Sze, together with the duplex polymerase chain reaction, provides accurate pre- and postnatal diagnosis of non-deletional Haemoglobin H disease and allows detailed genotype analyses using minimal quantities of DNA.

INTRODUCTIONTo report the sequential changes in corneal topography and astigmatism following limited macular translocation. CLINICAL PICTURE AND TREATMENT: A 45-year-old-man who underwent limited macular translocation for idiopathic subfoveal choroidal neovascularisation in the right eye was evaluated by corneal topography and manifest refraction preoperatively and serially for 1 year postoperatively.

OUTCOMEAn increase in astigmatism with corneal steepening along meridians corresponding to the area of chorioscleral infolding was observed and this persisted for 1 year after surgery. Vector-analysed astigmatic change showed significant surgically induced astigmatism of 2.18 dioptres (D) X 52.9 degrees, 2.17 D X 57.8 degrees and 2.56 D X 59.1 degrees at 2, 5 and 12 months after surgery respectively.

CONCLUSIONSurgically induced corneal changes are evident after limited macular translocation and may remain up to 1 year after surgery.

Astigmatism ; etiology ; Choroidal Neovascularization ; surgery ; Corneal Diseases ; etiology ; Corneal Topography ; Humans ; Male ; Middle Aged ; Ophthalmologic Surgical Procedures ; adverse effects

INTRODUCTIONThe aim of the study was to compare the visual performance of LASIK eyes measured using high-contrast logMAR letter charts under bright (photopic) and dim (mesopic) conditions.

MATERIALS AND METHODSA total of 46 subjects (35 +/- 8 years of age) undergoing LASIK procedures were recruited for the study. The best spectacle-corrected visual acuity (BSCVA) of each subject was measured using the high-contrast ETDRS logMAR chart under photopic and mesopic conditions at 3 visits: preoperative (Pre), 1 month postoperative (Post1) and 3 months postoperative (Post3). The differences in logMAR scores for the right eyes only were analysed for the Pre-Post1 (n = 46), Pre-Post3 (n = 18) and Post1-Post3 (n = 16) comparisons.

RESULTSThe logMAR scores of subjects were worse at the 1-month postoperative visit than preoperatively, and improvement in visual performance was seen at the 3-month postoperative visit. These changes in visual performance became more evident under mesopic conditions. The means and standard errors of the differences in logMAR scores for the Pre-Post3 (0.097 +/- 0.020) were slightly larger than those of the Pre-Post1 (-0.067 +/- 0.019) and Post1-Post3 (0.031 +/- 0.012) comparisons. Under mesopic conditions, the visual performance of the subjects was statistically significant for the 3 comparisons, but not under photopic conditions.

CONCLUSIONHigh-contrast logMAR chart performed under mesopic conditions has the potential to replace visual acuity measured under photopic conditions in providing more reliable representation of postoperative visual outcomes of LASIK eyes. Eye doctors should consider performing this vision test routinely to gauge the success of LASIK surgery.

Adult ; Contrast Sensitivity ; Female ; Humans ; Keratomileusis, Laser In Situ ; adverse effects ; Lighting ; Male ; Middle Aged ; Reproducibility of Results ; Vision Disorders ; diagnosis ; etiology ; Vision Tests ; methods ; Visual Acuity