Santiago García-Lázaro

The Tear Film and the Optical Quality of the Eye

The stability of the tear film plays an important role in the optical quality of the eye. Various methods have been developed to quantify the contribution of the tear film to optical quality, including the double-pass optical method, Hartmann-Shack wavefront sensing, videokeratoscopy, retroillumination analysis, and interferometry. In addition to assessing the effect of tear film irregularities, these methods can aid in the diagnosis of dry-eye related conditions and the monitoring of therapy. This review describes the methodologies used to assess the relationship between the tear film and optical quality of the eye and summarizes the most important findings obtained with these methods with regard to the healthy human eye, the dry eye, and the effect of artificial tear instillation.

Visual function after bilateral implantation of a new zonal refractive aspheric multifocal intraocular lens

PURPOSE: To evaluate visual function after bilateral implantation of a zonal refractive aspheric multifocal intraocular lens (IOL). SETTING: Private practice surgery center, Valencia, Spain. DESIGN: Cohort study. METHODS: Consecutive eyes with cataract had bilateral implantation of Lentis Mplus LS‐312 multifocal IOLs. Distance, intermediate, and near visual acuities; contrast sensitivity; defocus curves; and a quality‐of‐vision questionnaire, including presence of halos or dysphotopsia, were evaluated 6 months postoperatively. A control group of age‐matched monofocal pseudophakic patients was included to compare contrast sensitivity function. RESULTS: In the multifocal group, the mean binocular corrected distance visual acuity (logMAR) was −0.04 ± 0.07 at 6 m, 0.11 ± 0.10 at 1 m, and 0.06 ± 0.07 at 40 cm. The defocus curve showed little intermediate vision drop off. Photopic contrast sensitivity for distance was similar to the monofocal IOL contrast sensitivity function, while photopic contrast sensitivity for near and mesopic contrast sensitivity for distance with or without glare was reduced at high frequencies. The mean patient satisfaction was 8.09 ± 1.30 (scale 0 to 10); 84.4% of patients were completely independent of spectacles. Moderate halos, glare, and night‐vision problems were reported by 6.2%, 12.5%, and 15.6% of patients, respectively. CONCLUSION: The new‐generation multifocal IOL provided adequate distance, intermediate, and, to a lesser extent, near vision with high rates of spectacle freedom. Halos occurred, and other photic phenomena should be expected in a small percentage of patients. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Optical quality differences between three multifocal intraocular lenses: bifocal low add, bifocal moderate add, and trifocal.

PURPOSE To compare the in vitro optical quality at different focal points of two new bifocal intraocular lenses (IOLs) and one new trifocal IOL. METHODS The AcrySof ReSTOR SV25T0 (+2.5 diopter [D] add) and the AcrySof ReSTOR SN6AD1 (+3.0 D add) with two main foci (Alcon Laboratories, Fort Worth, TX) and the AT LISA tri 839MP with three main foci (Carl Zeiss Meditec, Dublin, CA) were evaluated. The optical quality of the IOLs was measured with the PMTF optical bench (LAMBDA-X, Nivelles, Belgium). The optical quality of the IOLs was quantified by the modulation transfer function (MTF) at five different focal points (0.0, -1.5, -2.0, -2.5, and -3.0 D) and for 3.0- and 4.5-mm apertures. The through-focus MTF of the IOLs was also recorded. RESULTS For the 0.0 D focal point, the AcrySof ReSTOR (+2.5 D add) obtained the highest MTF values for all apertures. For the -2.5 D focal point, the AcrySof ReSTOR (+3.0 D add) showed the highest MTF values for 3.0 mm. For the -3.0 D focal point at 3.0- and 4.5-mm aperture, the best values were obtained with the AcrySof ReSTOR (+3.0 D add) and the AT LISA, respectively. For the -1.5 D focal point, the trifocal IOL provided better values. For the -2.0 D focal point, all IOLs provided comparable results. The through-focus MTF curves showed three and two peaks for the trifocal and bifocal IOLs, respectively. CONCLUSIONS The trifocal IOL provides a better optical quality at the -1.5 D focal point. However, the optical quality of the trifocal IOL significantly decreases compared to the bifocal IOLs at far distance and -2.5 D focal points.

Optical quality after instillation of eyedrops in dry-eye syndrome.

PURPOSE: To study the effect of eyedrop instillation on the optical quality of the air–tear film interface at the anterior cornea in cases of dry eye. SETTING: University of Valencia, Valencia, Spain. METHODS: Corneal aberrations (total, spherical‐like, and coma‐like) were determined from corneal elevation maps and purpose‐designed software in cases of dry eye before, immediately after, and 10 minutes after lubricating eyedrop instillation (Blink Intensive Tears). All data were decomposed using Zernike polynomials to yield the root‐mean‐square wavefront deviations for pupil diameters of 3.0 mm and 5.5 mm. Outcome measures included comparison with clinical tear breakup time (TBUT). RESULTS: Wavefront higher‐order aberrations (HOAs) decreased significantly, by a factor of 2.5 on average, after artificial tear instillation with both pupil diameters (P<.01). The reduction was maintained 10 minutes after eyedrops instillation (P>.2). The mean TBUT was 3.6 seconds ± 1.7 (SD). Eyedrop instillation increased the TBUT values significantly (by approximately 60%) from baseline (P<.01). CONCLUSIONS: This method of air–tear film interface analysis facilitated evaluation of optical quality improvement after eyedrop instillation in patients with dry eye. After eyedrops were given, the increasingly regular tear film decreased HOAs, improving optical quality. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Long-term comparison of corneal aberration changes after laser in situ keratomileusis: Mechanical microkeratome versus femtosecond laser flap creation

PURPOSE: To compute and compare visual acuity, refractive outcomes, and anterior corneal aberration changes after myopic laser in situ keratomileusis (LASIK) with flap creation by a mechanical microkeratome and by a femtosecond laser. SETTING: Private practice refractive surgery center, Valencia, Spain. DESIGN: Comparative case series. METHODS: Patients were assigned to have LASIK flap creation with a mechanical microkeratome (Carriazo‐Barraquer) or a femtosecond laser (IntraLase). The Visx S2 excimer laser was used for myopic ablation in all cases. Main outcome measures included uncorrected and corrected distance visual acuities and the defocus equivalent. Higher‐order aberrations (HOAs) were computed from the anterior corneal surface measured with topography for 4.0 mm and 6.0 mm pupil diameters before and 48 months after surgery. RESULTS: The study evaluated 50 patients (98 eyes). The root mean square of HOAs increased postoperatively by a factor of approximately 1.9 in both groups and with both pupil diameters. There were no statistically significant differences between the 2 groups in the increase in anterior corneal aberrations, mean postoperative visual acuity, or residual refraction. All visual and optical performance metrics remained stable throughout the 4‐year follow‐up. There were no complications with flap creation and no postoperative complications. CONCLUSIONS: The increase in anterior corneal aberrations after myopic LASIK was similar after mechanical microkeratome and femtosecond laser flap creation. Visual acuity, refraction, and the optical quality of the cornea after LASIK remained stable through 4 years postoperatively in both groups. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Visual performance with simultaneous vision multifocal contact lenses.

Purpose:  The aim was to assess visual performance after PureVision high addition multifocal contact lens (PM) fitting through contrast sensitivity measured under different illumination levels for both distance and near.

Optical performance of two new trifocal intraocular lenses: through-focus modulation transfer function and influence of pupil size.

To compare the in vitro optical quality of two new trifocal intraocular lenses at different focal points as a function of pupil size.

High-resolution spectral domain optical coherence tomography technology for the visualization of contact lens to cornea relationships

Purpose: To study the utility of high-resolution spectral domain optical coherence tomography (HR SOCT) in imaging the contact lens (CL) to cornea relationships with advanced CL designs for ecstatic corneas and corneal refractive therapy. Methods: Copernicus HR SOCT (Optopol Technology SA, Zawiercie, Poland) was used to evaluate different lens materials and designs in situ and for the preliminary assessment of the materials and corneal response to hypoxic situations. Results: SOCT is capable of highlighting very subtle and interesting features of the CL-cornea relationships in a wide range of applications such as in rigid gas-permeable corneal and semiscleral lenses, in corneal refractive therapy and application of CLs in ocular pathology, and in the evaluation of the physiological response of the cornea. Conclusions: HR SOCT is a powerful tool capable of providing sharp images of the anterior ocular surface highlighting the relationship between lens and cornea with great detail. This methodology has several applications to enhance fitting modeling with modern designs for advanced CL treatments.

Visual performance of two simultaneous vision multifocal contact lenses

To evaluate and compare the visual performance of two simultaneous vision multifocal contact lenses (CLs).

Visual function through 4 contact lens-based pinhole systems for presbyopia

PURPOSE: To evaluate the effects of different contact lens–based artificial pupil designs on visual performance. SETTING: University of Valencia, Burjassot, Spain, and University of Manchester, Manchester, United Kingdom. DESIGN: Comparative case series. METHODS: Presbyopic patients were evaluated using 4 artificial pupil designs in the nondominant eye. Binocular uncorrected distance visual acuity (UDVA), binocular corrected distance visual acuity (CDVA), binocular uncorrected near visual acuity (UNVA), binocular distance‐corrected near visual acuity (DCNVA), defocus curve, binocular distance, and near contrast sensitivity under photopic and mesopic conditions, and stereoacuity were measured after contact lens fitting. RESULTS: The mean UDVA and CDVA ranged from 0.04 ± 0.05 (SD) to −0.01 ± 0.04 logMAR and from −0.02 ± 0.05 to −0.05 ± 0.03 logMAR, respectively. The UNVA and DCNVA ranged from 0.37 ± 0.11 to 0.42 ± 0.20 logMAR and from 0.35 ± 0.17 to 0.38 ± 0.12 logMAR, respectively. The difference in binocular distance contrast sensitivity was statistically significant between the pinhole systems and the control group (distance‐corrected patients without pinhole lens) for 6 cycles per degree (cpd), 12 cpd, and 18 cpd; for near vision, differences were also significant for 3 cpd at the 2 luminance levels (P<.05). Stereoacuity values for near vision were not significantly different between the 4 pinhole systems (P>.05). CONCLUSIONS: Soft contact lens apertures provide good visual acuity at distance, functional intermediate vision, and poor near visual acuity and stereoacuity. An improvement in visual performance with decreasing pupil diameter was not found. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.