Dark-adapted Pupil Sizes in a Prospective Evaluation of Laser in situ Keratomileusis Patients

Customized eye modeling for optical quality assessment in myopic femto-LASIK surgery

Refractive surgery is recognized as an effective method for myopia treatment, but it can induce night vision disturbances such as glare. We present an eye modeling method for the optical quality assessment in response to the structural changes in the eyes by femto-LASIK surgery. Customized eye models were built from the measurements of 134 right eyes pre- and post-operatively. Optical performance was evaluated using spot diagrams, point spread functions (PSFs), modulation transfer functions (MTFs), and chromatic aberrations at various fields (0°-30°), different pupil diameters (2-6 mm), and initial myopias (- 1.25 to - 10.5 D). Pupil size and initial myopia are the two major factors that affect visual performance of post-operative eyes. The results of spot diagrams, PSFs, and MTFs indicated that post-operative visual performance deteriorated as the visual field and pupil size increased, and it was significantly influenced by initial myopia. Post-operative chromatic aberrations were also affected by initial myopia. As pupil size increased, the post-operative longitudinal chromatic aberrations tended to decrease slightly, while the transverse chromatic aberrations remained similar. The use of eye modeling for refractive surgery assessment could possibly provide a more personalized surgical approach, could improve the prediction accuracy of refractive surgery outcomes, and promote the invention and development of better surgical methods.

Theoretical analysis of the effect of pupil size, initial myopic level, and optical zone on quality of vision after corneal refractive surgery

PURPOSE

To analyze the theoretical effect that pupil size, optical zone, and initial myopic level have on the final retinal image after corneal refractive surgery.

METHODS

A schematic myopic eye model corrected by the Munnerlyn formula was used to analyze the optical quality of the final retinal image. Root-mean-square radius spot and modulation transfer function were cal- culated by ray tracing to evaluate retinal image quality.

RESULTS

Pupil size had a negative effect on the retinal image only when it was greater than the diameter of the optical zone. In addition, the greater the initial myopic level, the more the pupil size affected image quality. Thus, a clear dependence exists between the initial myopic level and effect that the pupil size can have on the retinal image after laser refractive surgery.

CONCLUSIONS

Pupil size may be a risk factor for night vision disturbances, but only when it is larger than the theoretical optical zones utilized in this study. Its effect depends not only on the optical zone size, but also on the initial "myopic level. Therefore, this relationship should be taken into account during patient selection for refractive surgery

Contrast sensitivity after zyoptix tissue saving LASIK and standard LASIK for myopia with 6-month followup

This control-matched comparative study evaluated changes in contrast sensitivity after Zyoptix tissue-saving (TS) LASIK and Planoscan standard LASIK (Technolas 217z, Bausch & Lomb) for myopia 6 months postoperatively. 102 TS LASIK-treated eyes were matched with 102 standard LASIK-treated eyes (divided into low, moderate, and high groups). There were no significant differences in refraction outcomes between the groups postoperatively. In high group, a significant reduction in contrast sensitivity after TS LASIK was found at high spatial frequencies (P < .05) under photopic conditions and at middle to high spatial frequencies (P < .05) under mesopic conditions. And significant reduction was also found in standard LASIK at high spatial frequency (P < .05) under mesopic conditions. The reduction was significantly lower in TS LASIK than that in standard LASIK at high spatial frequencies (P < .05) under mesopic conditions. TS LASIK was prone to reduce mesopic contrast sensitivity of high myopia at high spatial frequencies.

[Long-term changes in pupil size after implantation of an Artisan phakic intraocular lens for correction of high myopia]

PURPOSE

To evaluate the long-term changes in pupil size after implantation of an Artisan phakic intraocular lens for correction of high myopia.

PATIENTS AND METHODS

Fourteen myopic eyes of seven patients were included in the study. Pupil size was measured under photopic conditions, under scotopic conditions after 10 min of dark adaptation, and after topical medical mydriasis. The pupil size was measured using the eye image of the OPD scan (Nidek).

RESULTS

The mean follow-up was 46 months after surgery. The mean photopic pupil diameter was 2.94+/-0.33 mm (range, 2.54-3.6 mm). The diameter of the scotopic pupil remained less than 6.0 mm in all patients (4.68+/-0.59 mm, with maximal pupil diameter of 5.67 mm). The mean pupil diameter after pharmacological dilation was also reduced (5.39+/-1.08 mm; range, 4.19-7.59 mm), with pupil dilation more than 7 mm in only one patient.

CONCLUSION

The iris-fixated intraocular lens mechanically limited pupil dilation in our patients. The long-term reduction in pupil size after Artisan phakic intraocular lens implantation may contribute to the maintenance of the quality of vision in scotopic conditions.

Correlation of Pupil Sizes Measured With a Mesopic Infrared Pupillometer and a Photopic Topographer

PURPOSE

To determine if videokeratography-based pupil measurements are an accurate method of estimating pupil size under mesopic conditions.

METHODS

Sixty patients who had a preoperative work-up for refractive surgery participated in the study. A single observer obtained detailed pupil measurements with the Colvard pupillometer under standardized lighting conditions. The same observer recorded pupil size measurements obtained automatically when corneal topographic analysis was performed with Humphrey videokeratography.

RESULTS

The Colvard pupillometry low light group was statistically different (P < .0001) from the Humphrey videokeratography automatic pupil measurement group. We calculated the value at which the Humphrey pupil measurements can accurately predict which patients would have pupil diameters > or = 6.5 mm under low mesopic conditions. By adding a constant of 2.6 mm to the Humphrey videokeratography pupil measurement, 100% of patients with a pupil diameter > or = 6.5 mm under low mesopic conditions were detected (sensitivity 100%). However, the ability to correctly reject those patients who do not have pupil diameters > 6.5 mm under low mesopic conditions was lower at 55% (specificity).

CONCLUSION

Videokeratography units can be used as a rapid, simple, and accurate method of predicting pupil size under mesopic conditions for potential refractive surgery patients and can provide a permanent record of pupil size. Care should be taken when relying on topography pupil sizes and more accurate measurements of mesopic and scotopic pupil sizes should be obtained.

Laser in situ keratomileusis for myopia and compound myopic astigmatism using the Technolas 217 scanning-spot laser

PURPOSE

To evaluate the safety, efficacy, predictability, and visual results of laser in situ keratomileusis (LASIK) using the Bausch & Lomb Technolas(R) 217 scanning-spot laser for the treatment of myopia and compound myopic astigmatism.

SETTING

Stanford Eye Laser Center, Stanford, California, USA.

METHODS

In a prospective study, 110 eyes of 58 patients with a mean spherical equivalent (SE) of -4.87 diopters (D) +/- 2.5 (SD) (range -1.0 to -11.4 D) had LASIK for myopia and compound myopic astigmatism using the Technolas 217 scanning-spot laser. The primary outcome variables included preoperative and postoperative best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA), achieved versus attempted correction, vector analysis of astigmatism, and complications.

RESULTS

One hundred ten eyes were available for analysis at 3 months. The mean SE refraction was reduced 95% (mean -0.23 +/- 0.4 D), and astigmatism was reduced 70% (mean 0.28 +/- 0.3 D). One day postoperatively, 100% of eyes had a UCVA of 20/40 or better, 96% had 20/25 or better, 77% had 20/20 or better, and 39% had 20/15 or better. At the 3-month examination, 100% of eyes had a UCVA of 20/40 or better, 95% had 20/25 or better, 83% had 20/20 or better, and 48% had 20/15 or better. Ninety percent of eyes were within +/-0.5 D of emmetropia. No eye lost 2 or more lines of BSCVA.

CONCLUSIONS

The Technolas 217 scanning-spot laser produced excellent postoperative UCVA and BSCVA. It was predictable, safe, and effective for the treatment of myopia and compound myopic astigmatism. Long-term follow-up is needed to assess the stability of the procedure.