Effect of a Yellow Filter on Contrast Sensitivity and Disability Glare After Laser in situ Keratomileusis Under Mesopic and Photopic Conditions

Visual function and subjective quality of life in Chinese cataract patients after implantation with aspheric intraocular lenses

PURPOSE

To evaluate and compare the objective and subjective visual function after implantation of 2 aspheric intraocular lenses (IOLs) in Chinese cataract patients.

METHODS

Forty-one eyes of 28 patients with cataract were randomly assigned to receive either the MC X11 ASP IOL or the AcrySof IQ IOL. Three months postoperatively, best-corrected visual acuity (BCVA), contrast sensitivity, wavefront aberrations, and subjective visual quality were measured. The degree of posterior capsule opacification (PCO) was recorded at last follow-up.

RESULTS

Postoperative mean monocular BCVA was 0.05±0.13 logMAR in the MC X11 group and 0.05±0.08 logMAR in the IQ group. There was no significant difference in visual acuity, contrast sensitivity, subjective visual quality, and degree of PCO between the 2 groups. For a 6-mm pupil diameter, the mean spherical aberration (Z40) was 0.075±0.076 µm in the MC X11 group and 0.056±0.111 µm in the IQ group. However, 45.5% and 57.9% of the eyes in the MC X11 and IQ groups had values >0.10 µm, respectively. The mean RMS values of the high-order aberrations were similar between the 2 groups except the higher fifth- and sixth-order aberrations, which were significantly higher in the MC X11 group.

CONCLUSIONS

Both IOLs provided similar and good visual outcomes. However, the data suggest that the amount of negative spherical aberration generated by current available aspheric IOLs might not be optimal for Chinese eyes.

Mesopic contrast sensitivity and ocular higher-order aberrations in eyes with conventional spherical intraocular lenses

PURPOSE

To investigate relationship between mesopic contrast sensitivity (CS) function and ocular higher-order aberrations in eyes implanted with conventional spherical intraocular lenses (IOL).

DESIGN

Prospective, nonrandomized case series.

METHODS

Sixty-eight eyes of 48 patients who attained best spectacle-corrected visual acuity (BSCVA) of 20/20 or better after phacoemulsification and spherical IOL implantation were included in the study. At 2 months postoperatively, mesopic CS was measured with the Mesotest II (Oculus; Wetsler, Germany), and ocular higher-order aberrations for a 4-mm pupil were measured with the Hartmann-Shack aberrometer. CS and letter CS under photopic conditions were recorded with the CSV-1000 charts (Vector Vision Co, Greenville, Ohio, USA).

RESULTS

There was significant correlation between mesopic CS and ocular fourth-order root mean square (RMS) of wavefront aberration (Spearman r(s) = -0.293; P = .017), but no correlation was found between mesopic CS and ocular third-order RMS (r(s) = 0.196; P = .189). Ocular third- and fourth-order RMS did not correlate with other parameters, including BSCVA, and CS and letter CS under photopic conditions.

CONCLUSIONS

Mesopic CS is significantly associated with ocular fourth-order RMS of wavefront aberrations in eyes implanted with conventional spherical IOLs.

Mesopic contrast sensitivity and ocular higher-order aberrations after overnight orthokeratology

PURPOSE

To investigate mesopic contrast sensitivity and night driving ability in eyes undergoing overnight orthokeratology, and to analyze the relationship among mesopic contrast sensitivity, ocular higher-order aberrations, and myopic correction.

DESIGN

Prospective, noncomparative, consecutive case series.

METHODS

In 44 eyes of 22 subjects (mean age +/- standard deviation [SD], 24.0 +/- 3.2 years) with orthokeratology, ocular aberrations and mesopic contrast sensitivity were determined before and three months after commencement of the procedure. Mean spherical equivalent refraction +/- SD was -2.34 +/- 0.99 diopters at baseline. Mesopic contrast sensitivity with and without glare was assessed using the Mesotest II (Oculus, Wetzlar, Germany).

RESULTS

Orthokeratology significantly reduced the log mesopic contrast sensitivity from 0.25 +/- 0.08 to 0.08 +/- 0.10 without glare (P < .0001, Wilcoxon) and from 0.21 +/- 0.11 to 0.07 +/- 0.10 with glare (P < .0001). The proportion of eyes that fulfilled the German standard recommendation level for night driving was 36%. The induced changes in log mesopic contrast sensitivity showed significant negative correlation with the changes in third-order (r = -0.490, P = .0013 without glare; r = -0.362, P = .0177 with glare; Spearman rank correlation coefficient) and fourth-order root mean square (r = -0.586, P = .0001 and r = -0.306, P = .0450, respectively). Furthermore, significant correlation was found between the amount of myopic correction and the induced changes in log mesopic contrast sensitivity (r = -0.442, P = .0038 without glare; r = -0.464, P = .0024 with glare). The induced changes in higher-order aberrations significantly correlated with the amount of myopic correction (P < .0001, Pearson correlation coefficient).

CONCLUSIONS

Mesopic contrast sensitivity after overnight orthokeratology is deteriorated significantly as ocular higher-order aberrations increase, and these changes depend on the amount of myopic correction.

The glare hypothesis of macular pigment function

PURPOSE

Discomfort and reduced visual performance due to glaring light conditions are common complaints for most individuals. Past studies have shown that macular pigment (MP) reduces discomfort due to glare. In this study, we evaluated whether MP was related to visual performance under glare conditions.

METHODS

Thirty-six healthy subjects participated (age range, 18 to 41). Spatial profiles of MP optical density were measured using heterochromatic flicker photometry with a Newtonian-view macular densitometer. Photostress recovery and grating visibility under veiling conditions were assessed in a Maxwellian-view optical system. Both experiments used six monochromatic lights (from 440 to 620 nm) and a broadband xenon white. For the veiling glare experiment, subjects fixated a 1 degrees diameter disk containing a black and white 100% contrast grating stimulus. The intensity of an annulus (the glare source) with an 11 degrees inner and 12 degrees outer diameter was adjusted by the subject until the grating stimulus was no longer seen. For the photostress recovery experiment, the time required to detect a 1 degrees -diameter grating stimulus (detailed above) after a 5-s exposure to a 2.5 microW/cm2, 5 degrees -diameter disk was recorded. Both central and eccentric (10 degrees temporal retina) viewing conditions were assessed.

RESULTS

MP at 30' eccentricity ranged from 0.08 to 1.04 OD, and was found to dramatically reduce the deleterious effects of glare. Visual thresholds under glare conditions were strongly related to MP density (e.g., r = 0.76, p = 0.0001 when using white light). Photostress recovery time, after exposure to xenon-white light, was significantly shorter for subjects with higher MP levels (r = -0.79, p = 0.0001). Both photostress recovery and veiling glare functions were well-described by the photopic spectral sensitivity function (Vlambda).

CONCLUSIONS

MP is strongly related to improvements in glare disability and photostress recovery in a manner consistent with its spectral absorption and spatial profile.

Contrast sensitivity and disability glare in patients with dry eye

PURPOSE

To evaluate contrast sensitivity and disability glare in patients with dry eye using the Contrast Glaretester 1000.

METHODS

Contrast sensitivity and disability glare were determined in 33 eyes of 33 patients with dry eye and 30 eyes of 30 healthy control subjects for six target sizes with a visual angle of 6.3-0.7 degrees using the Contrast Glaretester 1000, whose working mechanism is similar to that of the conventional perimetry instrument.

RESULTS

Contrast sensitivity was significantly worse in dry eye group when viewing all target sizes (reduction of 0.10-0.25 log contrast units, p < 0.01) except at 6.3 degrees. In the presence of glare, differences in log contrast sensitivity between the groups (0.10-0.25 units) were significant (p < 0.01) for all target sizes, with the dry eye group showing worse results. The reduction in contrast sensitivity induced by glare (disability glare) was significantly worse in the dry eye group versus the control group but only for the 2.5-degree size target, where 0.14 log contrast units were lost.

CONCLUSIONS

Contrast sensitivity with and without glare was significantly reduced in patients with dry eye compared with control subjects, but the number of log contrast units lost with glare (disability glare) was similar in the two groups, except for the 2.5-degree size target.