KIF21A variant R954W in familial or sporadic cases of CFEOM1.

PURPOSE: To demonstrate the clinical characteristics and determine mutations in the KIF21A gene, encoding a kinesin motor protein in patients with congenital fibrosis of the extraocular muscles (CFEOM) type 1. METHODS: Patients of five families with congenital fibrosis syndrome and two simplex patients with CFEOM underwent ophthalmologic examination and mutation analysis in the KIF21A gene. RESULTS: Clinical examination and passive motility testing prior to surgery met criteria for CFEOM. All patients had congenital restrictive ophthalmoplegia primarily affecting muscles innervated by the oculomotor nerve. Complete mutation screening in the KIF21A gene revealed the presence of the known and most common recurrent variant R954W in three families and in two simplex cases. Two families demonstrated linkage to chromosome 16. CONCLUSIONS: The patients included in the study had marked restriction of movement bilaterally with nearly complete loss of vertical ocular motility, graded reduction of horizontal motility, ptosis, and compensatory chin elevation. The phenotype was variable in patients carrying the same mutation. In one family, all patients were diagnosed with mental retardation, indicating that this syndrome might not only affect the development of cranial nerves, but can also be responsible for general neurologic dysfunction. The screening data suggest frequent and exclusive appearance of the R454W variant in sporadic and familial cases of CFEOM1 in Germany.

A correction formula for the real intraocular pressure after LASIK for the correction of myopic astigmatism.

PURPOSE: To create a correction formula to determine the real intraocular pressure (IOP) after LASIK considering the altered corneal thickness, corneal curvature, and corneal stability. METHODS: This prospective clinical trial comprised 101 eyes of 59 patients (34 women and 25 men) that underwent LASIK with a mean preoperative spherical equivalent refraction of -6.3 +/- 2.17 diopters (D) (-3.0 to -11.5 D). Mean patient age was 32 +/- 9 years. Preoperatively and 6 months postoperatively, IOP (by Goldmann applanation tonometry), keratometry (by topography), and central corneal thickness (CCT) (by ultrasound pachymetry) were evaluated. These parameters were measured in all patients between 8 and 11 o'clock in the morning. RESULTS: Due to the LASIK procedure, IOP was reduced from 16.5 +/- 2.1 mmHg (range: 12 to 22 mmHg) to 12.9 +/- 1.9 mmHg (range: 8 to 16 mmHg). Multiple linear regression analysis of the IOP values before and after LASIK showed a significant correlation between the measured IOP and CCT and keratometry values (R2=0.631; P<.001). After LASIK, the biomechanical bending strength of the cornea is reduced by the cut so that the measured IOP must be additionally corrected by 0.75 mmHg. An equation containing all three changes is given: IOP (real) = IOP (measured) + (540-CCT)/71 + (43-K-value)/2.7 + 0.75 mmHg. CONCLUSIONS: Intraocular pressure measurements after LASIK for the correction of myopia are inaccurate as a consequence of changes in CCT, corneal curvature, and corneal flap stability. After LASIK, the measured IOP should be corrected to avoid false low IOP applanation readings.

Diurnal fluctuation of higher order ocular aberrations: correlation with intraocular pressure and corneal thickness.

PURPOSE: Optimal wavefront-guided refractive corneal laser surgery requires sufficiently exact data of optical higher order aberrations. We investigated whether these aberrations had a systematic during-the-day variation, studied the range of variation, and changes in intraocular pressure and central corneal thickness. METHODS: In 22 eyes of 22 young volunteers the optical aberrations of higher order were measured by means of a Tscherning-type ocular aberrometer three times during one day (7 AM, 12 noon, 4 PM). In addition, in 12 of these eyes the intraocular pressure and central corneal thickness were measured. The intraocular wavefront aberration was computed using Zernike polynomials up to the sixth order, and Zernike coefficients of third and fourth order were analyzed. RESULTS: Only the coefficient Z 2/4 (C13) showed a significant increase during the day by a mean 0.016 microm. A significant regression could be detected between changes of coefficients Z3/3, Z-2/4, Z0/4, Z4/4, and changes of intraocular pressure or central corneal thickness during the day. CONCLUSIONS: Due to the small values, the measured during-the-day changes of higher order aberrations had no direct practical consequences for the aberrometry-guided corneal laser surgery. Alterations of some Zernike coefficients during the day may be explained by the biomechanical behavior of the cornea.