[Influence of corneal biomechanical properties on myopic regression after laser in situ keratomileusis]

BACKGROUND

Laser in situ keratomileusis is a safe and accepted method for correcting myopia. The operational results in terms of accuracy as well as the subjective acceptance of patients for corrections to - 8 D are now considered to be promising (Seiler, Refraktive Chirurgie der Hornhaut, 2000); however, postoperative results show individual patient problems in long-term stability. It is believed that the preoperative condition of the cornea (e.g. thickness, biomechanical properties) could have an influence on postoperative problems such as myopic regression.

METHOD

This study included a total of 46 eyes from 25 patients. At 3 months postoperatively, 15 patients (19 eyes) showed a SEQ of -0.50 D or more. Within this group, 11 patients (15 eyes) developed a regression (regression group) within the first 3 postoperative months. The remainder of the total group did not show any regression (stability group). The subjects of this study were on average 33 ± 8 years (stability group) and 31 ± 7 years old (regression group). The corneal thickness was tested and refractive error, visual acuity (BCVA/UCVA) and intraocular pressure was measured. In addition, the corneal hysteresis (CH) and corneal resistance factor (CRF) were determined.

RESULTS

The mean preoperative spherical equivalent refraction was -3.14 D ± 1.41 D (SE) in the stability group and - 6.47 D ± 1.40 D (p = 0.001)in the regression group. Also, the postoperative spherical equivalents were statistically significant different (p < 0.05). In contrast, the mean preoperative corneal thickness showed no differences in both groups (p = 0.96) (stability group 563 ± 36 µm and regression group 563 ± 28 µm).

CONCLUSIONS

The aim of the study to detect a possible causal relationship between myopia regression after LASIK and the biomechanical properties of the cornea and corneal thickness could not be clearly identified.

Molecular Genetic and Ocular Findings in Patients with Holt-Oram Syndrome

PURPOSE

The autosomal dominant Holt-Oram syndrome (HOS) is characterized by upper limb and cardiac septal defects. Mutations of the TBX5 gene have been identified as the underlying gene defect in HOS. Embryonic expression of TBX5 has been found in the human retina. This is the first report of ocular findings in two unrelated families with mutations in the TBX5 gene.

METHODS

Six living persons affected with HOS and 10 unaffected family members were subjected to mutation analysis and complete ophthalmological examination, including electrophysiological examinations (EOG and flash ERG).

RESULTS

A heterozygous single base-pain substitution in exon 5 (408C --> A) was detected in all affected patients. All examined affected patents were ophthalmological asymptomatic with normal EOG. A scotopic elongated b-wave latency was found in affected family members who were older than 35 years. The ERG was normal in the young patients.

CONCLUSIONS

Haploinsufficiency of TBX5 alters the dorsal-ventral polarity in developing eye vesicles without amy detected functional loss in human. Slight ERG abnormalities later in life may be a result of changes induced by the inner ganglion cell layer in the inner nuclear layer.

Haze-Bildung nach Vernetzungstherapie bei Keratokonus

The aim of cross-linking therapy is to prevent keratoconus progression and stabilize the present refractive situation. A 41-year-old man was treated with collagen cross-linking in one eye. Postoperatively there were a diffuse subepithelial opacification and a paracentral corneal thinning. This superficial scarring in the sense of a "haze" disappeared only gradually despite intensive therapy.