Angle κ Measurement and Its Correlation with Other Ocular Parameters in Normal Population by a New Imaging Modality.

SIGNIFICANCE: This study obtained normative database for angle κ using Orbscan 3. The average angle κ values were 2.3 ± 1.34° in the whole sample, 2.23 ± 1.36° in myopic eyes, and 3.3 ±1.5° in hyperopic eyes. This is very important to optimize refractive surgery outcomes. PURPOSE: The aim of this cross-sectional study was to obtain the value of mean angle κ in normal eyes of patients seeking laser vision correction, by the Orbscan 3. METHODS: The study was conducted on healthy eyes of people seeking laser refractive surgery. A total of 1815 eyes of 908 candidates were included. These were examined as a part of pre-operative assessment. Orbscan 3 was used to measure angle κ and its XY intercepts, keratometry readings, central corneal thickness, thinnest location, white-to-white diameter, and corneal asphericity of front surface (Qf) and back surface (Qb). RESULTS: The mean ± standard deviation angle κ in all eyes was 2.3 ± 1.34°. The values were 2.23 ± 1.36° in myopic eyes, 3.3 ±1.5° in hyperopic eyes, and 2.9 ±1.6° in emmetropic eyes. Positive correlation was found between angle κ and age, spherical equivalent, subjective sphere, and white-to-white diameter. On the other hand, axial length, average keratometry, central corneal thickness, pupil diameter, and asphericity Q front were negatively correlated with angle κ. CONCLUSIONS: The mean ± standard deviation angle κ value measured by the Orbscan 3 was 2.3 ± 1.34°. This could be attributed to different software used, in addition to the relatively high axial length in the studied eyes.

Effect of Pharmacological Mydriasis on the Intraocular Pressure in Eyes with Filtering Blebs Compared to Normal Eyes: A Pilot Study.

AIM: To test the effect of pharmacological mydriasis on intraocular pressure (IOP) in eyes with functioning blebs compared with normal eyes. PATIENTS AND METHODS: The cross-sectional study included 39 eyes, of which 19 eyes had filtering trabeculectomy blebs (group A), and 20 eyes with no previous surgeries (group B). IOP was measured using the Goldmann applanation tonometer before, and 30 min after the application of tropicamide 1% eye drops. RESULTS: In group A eyes, the IOP level changed from 13.68 ± 3.4 mmHg before pupillary dilatation, to achieve a level of 11.95 ± 3.03 mmHg following mydriasis, with an average IOP drop of 1.73 mmHg (p < 0.0001). On the other hand, the pre-dilatation IOP in group B eyes was 15.9 ± 3.00 mmHg, had increased after mydriasis to 18.4 ± 2.9 mmHg, with an average rise of 2.5 mmHg (p < 0.0001). The difference in IOP change following mydriasis between both groups was significant (p < 0.0001). CONCLUSION: Surprisingly, pharmacological pupillary dilatation resulted in a reduction of IOP in eyes with successful trabeculectomy, which is different from the usual effect of raising the IOP as in the control group. This effect has not been previously studied.