Visual Quality Assessment and Comparison of Monofocal and Multifocal Scleral Lens Designs: A Pilot Study.

PURPOSE: To compare visual quality, contrast sensitivity, stereopsis, subjective vision, and comfort between monofocal and multifocal scleral lens (SL) designs. METHODS: An experimental, cross over and short-term pilot study has been performed. Nineteen presbyopic patients (51.9±3.8 years) with regular corneas participated voluntarily in the study and Onefit MED monofocal and multifocal SL designs were fitted bilaterally. Subjective vision and comfort, contrast sensitivity function, stereopsis, high- and low-contrast visual acuity (VA) at 4 m and 40 cm under photopic and mesopic conditions, and defocus curves were measured. Data analysis was performed with nonparametric tests. P<0.05 was considered as statistically significant. RESULTS: Mean addition power of the prescribed lenses was 1.72±0.38 diopters. Multifocal design showed a statistically significant improvement for intermediate and near vision in the defocus curve under photopic and mesopic conditions (P<0.05), however, worsening in stereopsis (P<0.05) and contrast sensitivity for high spatial frequencies (P<0.05). Distance visual acuity (VA) showed significantly lower values under mesopic conditions for high- and low-contrast tests (P<0.05), and on low-contrast test under photopic conditions (P<0.001) with the multifocal design. CONCLUSION: Multifocal SLs showed better visual performance at intermediate and near distances without compromising distance vision under photopic conditions for a high-contrast test when compared with monofocal design.

Diurnal Variation in Accommodation, Binocular Vergence, and Pupil Size.

SIGNIFICANCE: Our results show significant diurnal variations in accommodative function and the magnitude of the phoria. Therefore, when comparing visual measures in clinical or laboratory settings, performing the visual examination at the same time of day (±1 hour) is encouraged. PURPOSE: The aim of this study was to evaluate the accommodation, binocular vergence, and pupil behavior on three different times during the day. METHODS: Twenty collegiate students (22.8 ± 2.1 years) participated in this study. Participants visited the laboratory on three different days at 2-hourly intervals (morning, 9:00 to 11:00 am ; afternoon, 2:00 to 4:00 pm ; evening, 7:00 to 9:00 pm ). The binocular vergence and accommodative function were measured using clinical optometric procedures, and the accommodative response and pupil function were evaluated in binocular conditions using the WAM-5500 autorefractometer. RESULTS: The accommodative amplitude for the right and left eyes showed statistically significant differences for the time interval ( P = .001 and P = .02, respectively), revealing higher accommodative amplitude in the morning and afternoon in comparison with the evening. Participants were more esophoric when assessed in the morning in comparison with the evening at far and near ( P = .02 and P = .01, respectively) and when assessed in the afternoon in comparison with the evening at far distance ( P = .02). The magnitude of accommodative response was higher in the morning, and it decreased throughout the day at 500 ( P < .001), 40 ( P = .05), and 20 cm ( P < .001). No statistically significant differences were obtained for any other variable. CONCLUSIONS: This study shows small diurnal variations in some accommodative and binocular vergence parameters, but no effects were observed for the pupil response. These outcomes are of special relevance for eye care specialists when performing repeated accommodative or binocular vergence measures. However, the diurnal variations were modest and may not influence a routine orthoptic examination.

A Comparison between Automated Subjective Refraction and Traditional Subjective Refraction in Keratoconus Patients.

SIGNIFICANCE: The performance of the Eye Refract (Luneau Technology, Chartres, France), a new instrument to perform aberrometry-based automated subjective refraction, has been previously evaluated in healthy subjects. However, its clinical implications in other ocular conditions are still unknown. PURPOSE: The purpose of this study was to evaluate the agreement between the Eye Refract and the traditional subjective refraction, as the criterion standard, in keratoconus patients with and without intracorneal ring segments (ICRSs). METHODS: A total of 50 eyes of 50 keratoconus patients were evaluated, dividing the sample into 2 groups: 27 eyes without ICRS (37.78 ± 9.35 years) and 23 eyes with ICRS (39.26 ± 13.62 years). An optometrist conducted the refraction with the Eye Refract, and another different optometrist conducted the traditional subjective refraction on the same day. Spherical equivalent (M), cylindrical vectors (J0 and J45), and corrected distance visual acuity were compared between both methods of refraction. In addition, Bland-Altman analysis was performed to assess the agreement between both methods of refraction. RESULTS: There were no statistically significant differences (P ≥ .05) between the Eye Refract and the traditional subjective refraction for all the variables under study in either group. Without ICRS, the mean difference and 95% limits of agreement (upper, lower) were -0.20 (+1.50, -1.89) D for M, -0.14 (+1.40, -1.68) D for J0, and +0.05 (+1.23, -1.14) D for J45. With ICRS, these values worsened to -0.62 (+3.89, -5.12) D for M, +0.06 (+2.46, -2.34) D for J0, and -0.02 (+2.23, -2.28) D for J45. CONCLUSIONS: The Eye Refract seems to offer similar results compared with the traditional subjective refraction in keratoconus patients not implanted with ICRS. However, some patients could show abnormal measurements, especially those with ICRS, who should be treated with caution in clinical practice.

Comparison Between Viscous Teardrops and Saline Solution to Fill Orthokeratology Contact Lenses Before Overnight Wear.

OBJECTIVE: To compare, in terms of efficacy, the differences between the use of saline solution and a viscous artificial tear to fill the lens during the first month of orthokeratology wear. METHODS: A pilot, double-masked, crossed, randomized, and prospective study was conducted. In this study, 20 subjects (14 males and 6 females) with a mean age of 16.29±6.22 years (range, 10-26) were fitted with orthokeratology contact lenses. For the study, nonpreserved 0.9% NaCl commercial saline solution (Avizor, Madrid, Spain) and nonpreserved artificial teardrops with 0.3% of hyaluronic acid (Ocudry 0.3%; Avizor, Madrid, Spain) were used. Corneal staining, tear break up time (TBUT), topography, refraction, visual acuity, and subjective comfort and vision with the visual analog scale (score from 0 to 10, being 10 better comfort and vision) were evaluated at 1 day, 1 week, and 1 month of contact lens wear. RESULTS: The corneal staining was statistically greater in the saline group than in the Ocudry group for the first day and during 1 week of wear (P<0.05). Comfort was found to be statistically better, with Ocudry 0.3% than saline solution, being 7.17±1.94 and 6.37±1.63, for the first day, and 8.78±0.43 and 8.15±0.62 for the day 28, respectively (P<0.05). However, no differences were found for subjective vision scores, TBUT, spherical equivalent, best-corrected visual acuity and uncorrected visual acuity, and mean keratometry between groups for any visit (P>0.05). CONCLUSION: Viscous artificial tears improve the subjective comfort of patients and reduce the corneal staining, compared with saline solution during the orthokeratology lenses fitting process. However, no differences between solutions for the treatment efficacy, in vision and corneal topography, were found.

Visual quality assessment and comparison of two multifocal scleral lens designs.

PURPOSE: To analyze the visual quality of a new multifocal scleral lens with a customized decentred optic zone compared to a conventional design by measuring visual acuity, contrast sensitivity function, stereopsis, subjective vision and comfort after one month of wear. METHODS: Nineteen presbyopic subjects were fitted with two multifocal scleral lens designs: a conventional multifocal and a customized decentred optical zone design. All subjects wore both scleral lens designs for one month with a two-week washout period. The main variables evaluated included high and low-contrast visual acuity under photopic and mesopic light conditions, binocular defocus curves, contrast sensitivity function and a visual analogue scale (VAS) for subjective vision and comfort. RESULTS: Comparing the two scleral lens designs, statistically significant differences in visual acuity were found, highlighting the improvement in more than one chart line (6 letters) for low contrast near tests under photopic light conditions with the decentred optics lens design. VAS questionnaire scores also showed a significant improvement in distance and overall subjective vision with the decentred optics lenses. Contrast sensitivity function showed an improvement with decentred multifocal lenses at all spatial frequencies measured, being statistically significant for 12 cycles per degree. No differences in stereoacuity were found. CONCLUSION: Multifocal scleral lenses with a customized decentred optical zone proved to be a promising refractive correction in presbyopic subjects after one month of wear, offering good comfort and visual quality under photopic and mesopic light conditions.

Anterior, Posterior, and Thickness Cornea Differences after Scleral Lens Wear in Post-LASIK Subjects for One Year.

The aim of this study is to analyze the anterior and posterior corneal surface shape and the corneal thickness difference outcomes between before and after scleral lens (ScCL) wear in post-LASIK ectasia subjects for one year. Twenty eyes with post-LASIK ectasia wearing scleral lenses were evaluated in a visit before contact lens and after 1, 6, and 12 months. The study variables analyzed included the apex, nasal, temporal, inferior, and superior corneal thickness; the anterior and posterior surface corneal at corneal diameters of 8, 6, 4, and 2 mm, and high-contrast visual acuity. A statistically significant increment of corneal thickness (p < 0.05) was observed in the inferior area after 6 months and in the superior area in the 12-month follow-up after wearing ScCLs. The anterior corneal curvature presented a flattening and a statistically significant steepening (p < 0.05) in the central and peripheral radii, respectively, after one year. The posterior corneal curvature showed a significant (p < 0.05) steepening, which mainly affected the central region after one year. Despite these changes, high-contrast visual acuity with ScCL correction remained at the same values. The prolonged use of scleral lenses in post-LASIK subjects showed significant changes in the corneal curvature and thickness. These outcomes recommend more detailed and periodic topographic and vision quality checks to monitor the wear in ScCL patients.

Accuracy and precision of automated subjective refraction in young hyperopes under cycloplegia.

PURPOSE: To assess the agreement between the Eye Refract, an instrument to perform subjective automated refraction, and the traditional subjective refraction, as the gold standard, in young hyperopes under noncycloplegic and cycloplegic conditions. METHODS: A cross-section and randomized study was carried out, involving 42 participants (18.2 ± 7.7 years, range 6 to 31 years). Only one eye was chosen for the analysis, randomly. An optometrist conducted the refraction with the Eye Refract, while another different optometrist conducted the traditional subjective refraction. Spherical equivalent (M), cylindrical components (J0 and J45), and corrected distance visual acuity (CDVA) were compared between both refraction methods under noncycloplegic and cycloplegic conditions. A Bland-Altman analysis was performed to assess the agreement (accuracy and precision) between both refraction methods. RESULTS: Without cycloplegia, the Eye Refract showed significantly lower values of hyperopia than the traditional subjective refraction (p < 0.009), the mean difference (accuracy) and its 95% limits of agreement (precision) being -0.31 (+0.85, -1.47) D. Conversely, there were no statistical differences between both refraction methods under cycloplegic conditions (p ≥ 0.05). Regarding J0 and J45, both refraction methods manifested no significant differences between them under noncycloplegic and cycloplegic conditions (p ≥ 0.05). Finally, the Eye Refract significantly improved CDVA (0.04 ± 0.01 logMAR) compared with the traditional subjective refraction without cycloplegia (p = 0.01). CONCLUSIONS: The Eye Refract is presented as a useful instrument to determine the refractive error in young hyperopes, the use of cycloplegia being necessary to obtain accurate and precise spherical refraction.

OCT applications in contact lens fitting.

Optical Coherence Tomography (OCT) is a noninvasive, high-speed, high-resolution imaging technology based in the Michaelson interferometry. A near-infrared light beam is used to register the intensity variations for the light backscattered on each sample layer. Due to the high repeatability on corneal measurements, spectral domain OCT (SD-OCT) is the gold standard when talking about in vivo, non-invasive anterior segment imaging. Changes in the morphology of various ocular surfaces such as the cornea, conjunctiva, limbus or tear film with soft (SCL), rigid, corneal or scleral lens (SL) wear can be described by OCT measurements. For instance, evaluation of the corneoscleral region is essential on SL fitting. For orthokeratology lenses central epithelial thinning and peripheral thickening and their regression could be quantified with OCT after Ortho-K lens wear. Blood vessel compression on the landing zone as well as vault thickness and fluid reservoir (FR) turbidity could be imaged with OCT. Tear film evaluation on contact lens wearers is essential because its use could lead to variations on the biochemical components in tears. Changes in tear meniscus dynamics and several parameters such as volume (TMV), tear meniscus height (HMT) and turbidity could be determined with OCT and positively correlated with the instillation of different ophthalmic solutions with Non-Invasive Break Up Time (NIBUT) and Schirmer test values. This manuscript shows the increasing applicability of OCT technology for the in vivo characterization of contact lens fitting and interaction with the ocular surface in a faster, safer and non-invasive way. Future research will still allow exploring OCT imaging to its full potential in contact lens practice, as there is still a significant amount of information contained in the images that are not yet easy to extract, analyze and give clinical value.

Stabilization of comfort and visual quality after the insertion of soft contact lenses.

PURPOSE: To evaluate comfort, visual function, and in vivo wettability after the insertion of hydrogel and silicone hydrogel contact lenses for a better understanding of how long practitioners should wait for the initial evaluation of soft contact lenses. METHODS: A short-term prospective, contralateral, randomized, and participant-masked study was carried out. Twenty healthy participants (25.4 ± 2.6 years) were evaluated after the insertion of two different soft contact lenses at different times (1, 5, 10, 20, 30 min). Ocufilcon D (hydrogel) and Somofilcon A (silicone hydrogel) contact lenses were randomly assigned to both eyes of the same participant. Comfort, visual function under photopic conditions in terms of high-contrast visual acuity, low-contrast visual acuity, contrast sensitivity, and in vivo wettability were measured. RESULTS: There was an increase in comfort (p < 0.001), high-contrast visual acuity (p < 0.05), and contrast sensitivity (p < 0.001, only with silicone hydrogel) directly related to time after contact lens insertion. Besides, in vivo wettability suffered a statistically significant deterioration directly related to time with both contact lenses (p < 0.05). Except for comfort and contrast sensitivity, all the parameters stabilized their values 10 min after the insertion of both soft contact lenses. Additionally, in vivo wettability and visual acuity differences were found between hydrogel and silicone hydrogel contact lenses (p < 0.05). CONCLUSIONS: It would be possible to properly evaluate high-contrast visual acuity, low-contrast visual acuity, and in vivo wettability 10 min after the insertion of both soft contact lenses.

Melatonin-Eluting Contact Lenses Effect on Tear Volume: In Vitro and In Vivo Experiments.

(1) Background: The purpose of this study was to synthesize melatonin-eluting contact lenses (CLs) and evaluate both the ocular kinetics of the released melatonin and its effect on tear volume and intraocular pressure. (2) Methods: In vitro, melatonin-eluting CLs were synthesized by using non-functionalized (HEMA) and functionalized (HEMA/APMA) monomers. In vivo, a short-term prospective and randomized study was performed on 15 rabbits divided into two groups: 12 rabbits wearing functionalized CLs and 3 rabbits without CLs as a control. The melatonin levels in tears, aqueous humor, vitreous body and retina, tear volume, and intraocular pressure were measured for 8 h. (3) Results: In vitro, both monomers did not show differences in terms of melatonin loading and release (p ≥ 0.05). In vivo, the melatonin concentration was elevated in tears and aqueous humor after 2 and 4 h of wearing CLs, respectively (p < 0.05). Additionally, the CLs increased tear volume for 2 h (p < 0.05). (4) Conclusions: The melatonin-eluting CLs released their content over the ocular surface for at least 2 h, which was associated with a secretagogue effect on tear volume. However, the increased amount of melatonin found in the aqueous humor had no effect on intraocular pressure.

Contact lenses for pravastatin delivery to eye segments: Design and in vitro-in vivo correlations.

Oral administration of cholesterol-lowering statins, HMG-CoA reductase inhibitors, is associated with beneficial effects on eye conditions. This work aims to design contact lenses (CLs) that can sustainedly deliver pravastatin and thus improve the ocular efficacy while avoiding systemic side effects of statins. Bioinspired hydrogels were prepared with monomers that resemble hydrophobic (ethylene glycol phenyl ether methacrylate) and amino (2-aminoethyl methacrylamide hydrochloride) functionalities of the active site of HMG-CoA. Best performing CLs loaded >6 mg/g, in vitro fulfilled the release demands for daily wearing, and showed anti-inflammatory activity (lowering TNF-α). High hydrostatic pressure sterilization preserved the stability of both the drug and the hydrogel network. Ex vivo tests revealed the ability of pravastatin to accumulate in cornea and sclera and to penetrate through transscleral route. In vivo tests (rabbits) confirmed that, compared to eye drops and for the same dose, CLs provided significantly higher pravastatin levels in tear fluid within 1 to 7 h of wearing. Moreover, after 8 h wearing pravastatin was present in cornea, sclera, aqueous humour and vitreous humour. Strong correlations between percentages of drug released in vitro and in vivo were found. Effects of volume and proteins on release rate and Levy plots were identified.

Changes in visual quality with soft contact lenses after the instillation of hyaluronic acid eye drops.

PURPOSE: To evaluate the changes in visual function and anterior surface aberrations during soft contact lens (SCL) wear after the instillation of hyaluronic acid (HA) eye drops with different viscosity. METHODS: A prospective, randomized, and participant-masked study was performed. Twenty healthy participants (25.4 ± 2.6 years) were evaluated. Hydrogel (Ocufilcon D) and silicone-hydrogel (Somofilcon A) SCL were randomly assigned to both eyes of the same participant. Visual function in terms of high- and low-contrast corrected distance visual acuity (CDVA) and anterior contact lens surface aberrations (RMS HOA) were measured before and after the instillation, at different times, of different eye drops: saline (control) and 0.1%, 0.2%, and 0.3% HA. RESULTS: Compared with the saline solution, during hydrogel SCL wear, there was an improvement (P < 0.05) in high-contrast CDVA after 3 and 10 min with 0.1% HA, and after 5 and 20 min with 0.2% HA. During silicone-hydrogel SCL wear, there was a deterioration (P < 0.05) in high-contrast CDVA after 1 and 30 min with 0.3% HA. Additionally, during silicone-hydrogel SCL wear, there was also a deterioration (P < 0.05) in low-contrast CDVA after 5 and 20 min with 0.3% HA. In terms of RMS HOA, there were no clinically relevant changes with both SCL. CONCLUSIONS: The instillation of HA eye drops could have a different effect on visual quality depending on their concentration of HA, the contact lens material, its surface ionicity, or other physicochemical properties that should be studied in future studies.

Repeatability of Aberrometry-Based Automated Subjective Refraction in Healthy and Keratoconus Subjects.

PURPOSE: To compare the intersession repeatability of the Eye Refract, a new instrument to perform aberrometry-based automated subjective refraction, on healthy and keratoconus subjects. MATERIALS AND METHODS: A cross-sectional and randomized study was performed. A total of 64 participants were evaluated in the study, selecting one eye per participant randomly. The sample was divided into two different groups: 33 healthy subjects (38.85 ± 13.21 years) and 31 with keratoconus (37.29 ± 11.37 years). Three refractions per participant with the Eye Refract were performed on three different days, without cycloplegia. The repeatability analysis of refractive variables (M, J0, and J45), binocular corrected distance visual acuity (BCDVA), and spent time in refraction was performed in terms of repeatability (S r), its 95% confidence interval (r), and intraclass correlation coefficient (ICC). RESULTS: There were no statistically significant differences (P ≥ 0.05) between sessions in both groups for all refractive variables (M, J0, and J45) and BCDVA. Spent time in refraction was reduced as the sessions went by (P < 0.05). The Eye Refract was more repeatable for refractive errors assessment in healthy subjects (M : S r = 0.27 D; J0 : S r = 0.09 D; J45 : S r = 0.06 D) compared to those with keratoconus (M : S r = 0.65 D; J0 : S r = 0.29 D; J45 : S r = 0.24 D), while it was similar for BCDVA. CONCLUSIONS: The Eye Refract offered better repeatability to assess refractive errors in healthy subjects compared to those with keratoconus. Despite measurements being also consistent in keratoconus subjects, they should be treated with caution in clinical practice.

Comparison of Two Wavefront Autorefractors: Binocular Open-Field versus Monocular Closed-Field.

PURPOSE: To evaluate the agreement and repeatability between a new commercially available binocular open-field wavefront autorefractor, as part of the Eye Refract system, and a monocular closed-field wavefront autorefractor (VX110). METHODS: A cross-sectional, randomized, and single-masked study was performed. Ninety-nine eyes of 99 healthy participants (37.22 ± 18.04 years, range 8 to 69 years) were randomly analyzed. Three measurements with the Eye Refract and the VX110 were taken on three different days, under noncycloplegic conditions. Mean spherical equivalent (MSE), cylindrical vectors (J0 and J45), and binocular corrected distance visual acuity (BCDVA) were compared between both autorefractors. An intersession repeatability analysis was done considering the values of repeatability (S r ) and its 95% limit (r). RESULTS: The VX110 showed more negative values (P < 0.001) in terms of MSE in comparison with the Eye Refract (0.20 D). Regarding cylindrical vectors, J45 showed statistically significant differences (P=0.001) between both wavefront autorefractors, but they were not clinically relevant (<0.05 D). In BCDVA, there were no statistically significant differences (P=0.667) between both wavefront autorefractors. Additionally, the Eye Refract was more repeatable than the VX110 in terms of both MSE (S r EYE REFRACT = 0.21 D, S r VX110 = 0.53 D) and J0 (S r EYE REFRACT = 0.12 D, S r VX110 = 0.35 D). CONCLUSIONS: The Eye Refract provided enough accuracy and reliability to estimate refractive errors in different age groups, achieving better results than the VX110. Therefore, the Eye Refract proved to be a useful autorefractor to be incorporated into clinical practice.

Corneal surface wettability and tear film stability before and after scleral lens wear.

PURPOSE: The aim of this study was to evaluate the anterior surface of scleral contact lens and ocular surface wettability before and after one-month of scleral lens wear in patients with keratoconus. METHODS: Forty-nine patients with keratoconus (36.26 ± 9.03 years) were recruited. The sample was divided into two groups: patients with intrastromal corneal ring (KCICRS group) and patients without ICRS (KC group). TFSQ, Schirmer I test, Ocular Surface Disease Index (OSDI questionnaire), tear break-up time (TBUT) and corneal staining were evaluated in two different visits: Baseline (before lens wear) and one-month visit (10 min after lens removal). Visual Analog Scale (VAS questionnaire) was filled in just after inserting the lenses and just before removing them. TFSQ mean and inferior were evaluated over the contact lens surface at the moment of inserting the lens (baseline visit) and after 8 h of lens wear (one-month visit). RESULTS: Anterior corneal surface TFSQ values increased in all groups after scleral lens wear (p < 0.05). However, there were no statistical differences found at the moment of inserting or after 8 h of lens wear on previous contact lens surface TFSQ (p > 0.05). No changes were found in tear volume for total and in KC and KCICRS groups (p > 0.05). For all groups, there was a statistical decrease of TBUT (p < 0.05). In addition, OSDI score, corneal staining and VAS score improved after scleral lens wear from baseline in total and in both KC and KCICRS groups (p < 0.05). CONCLUSION: The scleral contact lens surface keeps its wettability after one-month of wear. However, the wettability of the ocular surface is worse after contact lens wearing.

Evaluation of tear meniscus by optical coherence tomography after different sodium hyaluronate eyedrops instillation.

PURPOSE: To evaluate changes in tear meniscus dynamics using optical coherence tomography (OCT) after the instillation of different concentrations of sodium hyaluronate (SH) ophthalmic solutions. METHODS: An experimental, double-masked, randomized study was performed. Twenty-three healthy subjects (16 women and seven men; mean age 23.57 ± 2.56 years) participated in this study. About 35 µl of 0.1%, 0.2%, 0.3% SH ophthalmic solutions and saline solution was instilled in a randomly assigned eye. Tear meniscus measurements (height, depth and turbidity) were taken with OCT at 30 seconds and 1, 3, 5, 10 and 20 min after instillation. Subsequently, the Schirmer test and tear break-up time (TBUT) were evaluated. RESULTS: Tear meniscus depth and tear meniscus height showed a significant increase with all solutions compared to basal values: up to 3 min for 0.1% SH, up to 5 min for 0.2% and up to 10 min for 0.3% SH ophthalmic solution. Tear meniscus turbidity was also increased at 30 seconds for 0.1%, 0.2% and 0.3% SH artificial tears (p < 0.05). This increase remained significant for up to 1 min for 0.2% and 0.3% SH solutions (p < 0.05). After 5 min of saline and 0.1% SH instillation, the turbidity was lower than basal values (p < 0.05). There was a significant increase in the TBUT for all solutions after instillation (p < 0.05). No differences between the Schirmer pre- and postinstillation were found (p > 0.05). Finally, the comfort was significantly improved for all ophthalmic solutions (p < 0.05). CONCLUSION: Sodium hyaluronate (SH) ophthalmic solutions increase residence time in healthy subjects and are positively correlated with its concentration and therefore the viscosity.

Posterior cornea and thickness changes after scleral lens wear in keratoconus patients.

PURPOSE: To evaluate the changes in the corneal thickness, anterior chamber depth and posterior corneal curvature and aberrations after scleral lens wear in keratoconus patients with and without intrastromal corneal ring segments (ICRS). METHODS: Twenty-six keratoconus subjects (36.95 ±â€¯8.95 years) were evaluated after 8 h of scleral lens wear. The subjects were divided into two groups: those with ICRS (ICRS group) and without ICRS (KC group). The study variables evaluated before and immediately after scleral lens wear included corneal thickness evaluated in different quadrants, posterior corneal curvature at 2, 4, 6 and 8 mm of corneal diameter, posterior corneal aberrations for 4, 6 and 8 mm of pupil size and anterior chamber depth. RESULTS: There was a statistically significant corneal thinning (p < 0.05) in the inferior region of the KC group and in the superior region of the ICRS group. No change (p > 0.05) in the anterior chamber depth was found. The KC group showed a steepening (p < 0.05) in the temporal quadrant and a flattening that mainly affected to the superior-nasal quadrant. The ICRS group showed a steepening (p < 0.05) that mainly affected to the superior-nasal quadrant. Regarding posterior corneal aberrations, only changes (p < 0.05) in Z4 for 8 mm and Z8 for 4 mm were found in the KC group. CONCLUSIONS: Short-term scleral lens wear showed a thinning of the cornea and changes in the posterior corneal curvature affects different regions in keratoconus patients with and without ICRS.

Comparison Between Aberrometry-Based Binocular Refraction and Subjective Refraction.

PURPOSE: We evaluate the efficacy of a new system of binocular refraction, mainly based on ocular aberrometry (EYER) and compare it with the traditional subjective refraction as gold standard. METHODS: A prospective, double blind, and transversal study was performed on 99 subjects (35 men, 64 women; mean age 37.22 ± 18.04 years; range, 7-70 years). Refractive surgery or irregular cornea were considered exclusion criteria. Subjective refraction was performed by three different optometrists and EYER by other optometrists on three different days randomly. The binocular best corrected visual acuity (BBCVA), subjective vision evaluated with visual analogue scale (VAS), refraction spent time, and mean spherical equivalent (MSE), and vertical and oblique cylindrical components (J0 and J45) were analyzed. RESULTS: A positive strong correlation between EYER and subjective refraction was found for MSE (Pearson, 0.984; P < 0.001) and J0 and J45 (Pearson, 0.837; P < 0.001 and Pearson, 0.852; P < 0.001, respectively) in the total group. There were no statistically significant differences for BBCVA (P < 0.05). The VAS scores were 84.29 ± 12.29 with the EYER and 86.89 ± 12.38 with subjective refraction (P = 0.031). The spent time to perform the refraction was statistically lower (P < 0.05) with the EYER compared to conventional subjective refraction for all groups. CONCLUSIONS: The EYER system showed similar results in terms of spherical and cylindrical components, visual acuity being the spent time in the refraction lower than conventional subjective refraction. TRANSLATIONAL RELEVANCE: This new objective refraction system provides less chair spent time with similar results than subjective refraction.

Accuracy and precision of automated subjective refraction in young hyperopes under cycloplegia

Purpose: To assess the agreement between the Eye Refract, an instrument to perform subjective automated refraction, and the traditional subjective refraction, as the gold standard, in young hyperopes under noncycloplegic and cycloplegic conditions. Methods: A cross-section and randomized study was carried out, involving 42 participants (18.2 ± 7.7 years, range 6 to 31 years). Only one eye was chosen for the analysis, randomly. An optometrist conducted the refraction with the Eye Refract, while another different optometrist conducted the traditional subjective refraction. Spherical equivalent (M), cylindrical components (J0 and J45), and corrected distance visual acuity (CDVA) were compared between both refraction methods under noncycloplegic and cycloplegic conditions. A Bland-Altman analysis was performed to assess the agreement (accuracy and precision) between both refraction methods. Results: Without cycloplegia, the Eye Refract showed significantly lower values of hyperopia than the traditional subjective refraction (p < 0.009), the mean difference (accuracy) and its 95% limits of agreement (precision) being -0.31 (+0.85, -1.47) D. Conversely, there were no statistical differences between both refraction methods under cycloplegic conditions (p ≥ 0.05). Regarding J0 and J45, both refraction methods manifested no significant differences between them under noncycloplegic and cycloplegic conditions (p ≥ 0.05). Finally, the Eye Refract significantly improved CDVA (0.04 ± 0.01 logMAR) compared with the traditional subjective refraction without cycloplegia (p = 0.01). Conclusions: The Eye Refract is presented as a useful instrument to determine the refractive error in young hyperopes, the use of cycloplegia being necessary to obtain accurate and precise spherical refraction. (AU)