Psychological factors and sex differences in acceptance of monovision

BCLA CLEAR Presbyopia: Management with contact lenses and spectacles

This paper seeks to outline the history, market situation, clinical management and product performance related to the correction of presbyopia with both contact lenses and spectacles. The history of the development of various optical forms of presbyopic correction are reviewed, and an overview is presented of the current market status of contact lenses and spectacles. Clinical considerations in the fitting and aftercare of presbyopic contact lens and spectacle lens wearers are presented, with general recommendations for best practice. Current options for contact lens correction of presbyopia include soft simultaneous, rigid translating and rigid simultaneous designs, in addition to monovision. Spectacle options include single vision lenses, bifocal lenses and a range of progressive addition lenses. The comparative performance of both contact lens and spectacle lens options is presented. With a significant proportion of the global population now being presbyopic, this overview is particularly timely and is designed to act as a guide for researchers, industry and eyecare practitioners alike.

Changes in Keratometric Values and Corneal High Order Aberrations After Hydrogel Inlay Implantation

PURPOSE

We sought to analyze surgically induced refractive change (SIRC) and change in high-order aberration after Raindrop corneal inlay insertion (ReVision Optics, Lake Forest, CA), and assess the extent to which Raindrop corneal inlay insertion could correct presbyopia.

DESIGN

Interventional case series.

METHODS

Seventeen patients were included if they had a corneal thickness ≥500 μm and a stable manifest spherical equivalent refraction between 0.50 and +1.00 diopters (D). The Raindrop corneal inlay was implanted on the stromal bed of a femtosecond laser-assisted generated flap of nondominant eyes. Manifest refraction, corneal powers, and corneal high-order aberrations were measured preoperatively and at 3 and 12 months postoperatively.

RESULTS

The SIRC by manifest refraction was 0.99 ± 0.26 D. The changes derived from simulated keratometry (K), true net power, and equivalent K reading (EKR) at 1.0-4.0 mm were greater than the SIRC (all P < .01) while the change in EKR at 6.0 mm was less than the SIRC (P < .01). The changes in EKR 5.0 mm, automated K, and EKR 4.5 mm did not differ significantly from the SIRC (P = .81, .29, and .09, respectively), and the difference was the least for EKR 5.0 mm. In analysis of high-order aberrations, only spherical aberration showed statistically significant difference between preoperative and postoperative on both anterior cornea and total cornea (all P < .01).

CONCLUSION

Raindrop corneal inlay corrects presbyopia via increasing negative spherical aberration. The equivalent K reading at 5.0 mm accurately reflected the SIRC, and would be applicable for intraocular power prediction before cataract surgery.

A relationship between tolerance of blur and personality

PURPOSE

To determine whether tolerance of dioptric spherical defocus is related to measures of personality. Clinical observations suggest that there is individual variability in tolerance of blur.

METHODS

A computer-controlled Badal optometer was used to measure just-noticeable blur and just-objectionable blur responses to positive lens defocus. Blur tolerance was defined as the difference between these two responses. A personality battery was administered consisting of the NEO-FFI (Neuroticism-Extroversion-Openness-Five Factor Inventory) and the California Adult Q-sort (general measures), as well as individual measures (hypothesis-driven scales) of perfectionism, neuroticism, highly sensitive person, ego resiliency, need for structure, and negative emotionality. Ninety-nine normally sighted subjects (median age, 21 years, median refractive error 0.6 DS) completed both parts of the study.

RESULTS

Within-subject blur tolerance measures with three different pupil sizes correlated highly (r(s) = 0.79-0.86), implying good repeatability. There was a wide range of individual blur tolerance (0.0-2.7 D). The personality questionnaires exhibited acceptable reliability (Cronbach's α = 0.67-0.91). Two perfectionism scales correlated significantly with blur tolerance (r = 0.25 and 0.27). The 15 questionnaire items that correlated most with blur tolerance were factor analyzed and yielded two conceptually meaningful factors (both α = 0.76). The "low self confidence" and "disorganization" factors correlated positively with blur tolerance (r = 0.38 and 0.36, respectively) and their composite correlated with blur tolerance (r = 0.46).

CONCLUSIONS

These results provide the first evidence of a relationship between personality and tolerance of blur. Tolerance of blur may be related to perception of image quality. If so, personality may influence refractive error correction and development and other choices that are made when presented with degraded images.

Multifocal corneal ablation for hyperopic presbyopes

PURPOSE

To investigate the clinical results of multifocal wavefront-guided corneal ablation with a central near zone in hyperopic presbyopes.

METHODS

Twenty-seven patients (54 eyes) were analyzed retrospectively. Monocular near and distance uncorrected visual acuity (UCVA) and binocular near and distance UCVA were measured preoperatively, and the near addition power and the manifest refraction were obtained. Measurements of spherical aberration, coma, total higher order aberration, and contrast sensitivity for high and low photopic conditions were performed. All patients received multifocal corneal ablations with a central near zone using the VISX CustomVue System and were examined at 1 month (48 eyes), 2 months (42 eyes), and 6 months (28 eyes) after surgery.

RESULTS

Of 14 patients, 9 (64.3%) achieved both 0.8 or better in binocular distance UCVA and 0.65 or better in binocular near UCVA, and the spherical equivalent refraction and near addition power decreased from +1.16+/-0.82 diopters (D) to +0.33+/-0.45 D and from 2.35+/-0.44 D to 1.42+/-0.62 D at 6 months after surgery, respectively. No significant changes were noted in total higher order aberration and contrast sensitivity, whereas spherical aberration coefficients (Z-12) changed from positive to negative.

CONCLUSIONS

Multifocal wavefront-guided refractive surgery in presbyopia offered effective correction in hypermetropia and satisfactory near vision without significant increase in comeal total higher order aberration or significant decrease in contrast sensitivity.

Contact lens correction of presbyopia

The contact lens wearing presbyopic population is underserved worldwide. There are several available options, including single vision contact lenses and spectacle over-correction for near, monovision, rigid gas permeable (GP) multifocal and bifocal lens designs and soft bifocal lens designs. This paper presents an overview of the latest research and clinical experience as it pertains to these forms of correction. Recent comparative studies concluded that contact lens multifocals perform better in many different forms of visual measurements, in some cases performing similar to best spectacle correction, than monovision wearers. The future appears to be very promising for multifocal GP and soft lens modalities.

Monovision: a review

In presbyopia, patients can no longer obtain clear vision at distance and near. Monovision is a method of correcting presbyopia where one eye is focussed for distance vision and the other for near. Monovision is a fairly common method of correcting presbyopia with contact lenses and has received renewed interest with the increase in refractive surgery. The present paper is a review of the literature on monovision. The success rate of monovision in adapted contact lens wearers is 59-67%. The main limitations are problems with suppressing the blurred image when driving at night and the need for a third focal length, for example with computer screens at intermediate distances. Stereopsis is impaired in monovision, but most patients do not seem to notice this. These limitations highlight the need to take account of occupational factors. Monovision could cause a binocular vision anomaly to decompensate, so the pre-fitting screening should include an assessment of orthoptic function. Various methods have been used to determine which eye should be given the distance vision contact lens and the literature on tests of ocular dominance is reviewed. It is concluded that tests of blur suppression are most likely to be relevant, but that ocular dominance is not fixed but is rather a fluid, adaptive, phenomenon in most patients. Suitable patients can often be given trial lenses that allow them to experiment with monovision in real world situations and this can be a useful way of revealing the preferred eye for each distance. Of course, no patient should drive or operate machinery until successfully adapted to monovision. Surgically induced monovision is less easily reversed than contact lens-induced monovision, and is only appropriate after a successful trial of monovision with contact lenses.