Intraocular Straylight and Multifocal Soft Contact Lens Fit With a Myopia Control Approach.

OBJECTIVES: Center-distance multifocal contact lenses (MFCLs) are used to slow myopia progression. We examined the effect of two MFCLs on intraocular straylight values in myopic individuals. METHODS: Twenty-five young myopic adults were enrolled and were fit with three contact lenses (Biofinity sphere, Biofinity Multifocal, and NaturalVue Multifocal) in a random order over two study visits. Pupil size (NeurOptics VIP-300, Laguna Hills, CA) and contact lens centration were measured. Right eye intraocular straylight measurements were collected (OCULUS C-Quant; Wetzlar, Germany) and compared with a spectacle trial lens. Log straylight (LogSL) values and straylight residuals were analyzed using repeated-measures analyses of variance with Tukey-corrected post hoc t -tests. RESULTS: The mean participant age (±SD) was 24.1±1.5 years, and right eye spherical equivalent refractive error was -3.38±1.53 DS. There was no difference in mesopic pupil size between visits ( P =0.68) and no difference in contact lens centration between lenses ( P =0.99). LogSL values differed by lens type ( P =0.004). LogSL with the spectacle trial lens was significantly greater than with each contact lens type (all P <0.05), but there were no significant differences in LogSL between the three contact lenses (all P >0.05). There was no difference between the three contact lens designs for straylight residuals ( P =0.33). CONCLUSIONS: Measured intraocular straylight for both MFCLs was not different than with a spherical soft contact lens. A significant increase in intraocular straylight with spectacle trial lens correction was observed compared with all contact lenses.

Thermal effect on eyelid and tear film after low-level light therapy and warm compress.

CLINICAL RELEVANCE: The warming effect of low-level light therapy may contribute to its therapeutic mechanism which is beneficial for dry eye management. BACKGROUND: Low-level light therapy is proposed to work via cellular photobiomodulation and a potential thermal effect in dry eye management. This study examined the change in eyelid temperature and tear film stability after low-level light therapy compared to warm compress. METHODS: Participants with no to mild dry eye disease were randomised into control, warm compress, and low-level light therapy groups. The low-level light therapy group was treated with Eyelight mask (633 nm) for 15 minutes, the warm compress group with Bruder mask for 10 minutes, and the control group with an Eyelight mask having inactive LEDs for 15 minutes. Eyelid temperature was measured using the FLIR One® Pro thermal camera (Teledyne FLIR, Santa Barbara, CA, USA), and clinical measures of tear film stability were evaluated before and after treatment. RESULTS: Thirty-five participants (mean age ± SD, 27.3 ± 4.3 years) completed the study. Eyelid temperatures for external upper, external lower, internal upper and internal lower eyelids were significantly greater in the low-level light therapy and warm compress groups immediately after treatment compared to the control group (all p < 0.001). No difference in temperature was observed between the low-level light therapy and warm compress groups at all time points (all p > 0.05). Tear film lipid layer thickness was significantly greater after treatment (mean (95% CI), 13.1 nm (5.3 to 21.0), p < 0.005) but not different between groups (p > 0.05). CONCLUSION: A single treatment of low-level light therapy increased eyelid temperature immediately after treatment, but the increase was not significantly different from warm compress. This suggests that thermal effects may in part contribute to the therapeutic mechanism of low-level light therapy.

A Hue-Value method for semi-automated assessment of Lid Wiper Epitheliopathy.

BACKGROUND: Lid wiper epitheliopathy (LWE) is a marker of an abnormal lid/cornea interaction. This study proposes an automated Hue-Value grading algorithm of LWE staining following manual selection of the region of interest. METHODS: Images of LWE staining were processed using Hue and Value from HSV (Hue-Saturation-Value) color space with a custom MATLAB program. Thirty-one images were successfully analyzed. Examiners analyzed images in random order twice, separated by more than a week. Bland Altman and Intraclass Correlation Coefficients (ICC) were performed. RESULTS: There was no difference (p > 0.05) between upper (UL) and lower (LL) eyelids for LWE height (UL: 0.12 ± 0.12 mm, LL: 0.12 ± 0.07 mm), width (UL: 10.70 ± 3.84 mm, LL: 10.26 ± 3.49 mm), or area (UL: 2.85 ± 2.67 mm2, LL: 2.63 ± 1.71 mm2). There was no between examiner difference for all eyelid LWE height or area (p > 0.05), but a difference in LWE width (0.16 mm; p = 0.031). ICC for LWE height, width and area were 0.996 (95% CI: 0.993 to 0.998), 0.997 (95% CI: 0.992 to 0.998) and 0.999 (95% CI: 0.998 to 0.999). There was no between examiner difference for height or area (p > 0.05) for UL, but a difference in LWE width (0.28 mm; p = 0.026). ICC for height, width and area were 0.999 (95% CI: 0.996 to 1.00), 0.995 (95% CI: 0.982 to 0.999) and 1.00 (95% CI: 0.999 to 1.00). There was no difference in LWE height, width or area for LL (all p > 0.05). ICC were 0.991 (95% CI: 0.973 to 0.997) for height, 0.998 (95% CI: 0.995 to 0.999) for width and 0.997 (95% CI: 0.990 to 0.999) for area. CONCLUSIONS: This novel method results in highly repeatable interexaminer measures of LWE staining after general lid region delineation. Small differences in LWE width were observed between examiners.

Contrast Sensitivity with Center-distance Multifocal Soft Contact Lenses.

SIGNIFICANCE: The contrast sensitivity (CS) function provides a more detailed assessment of vision than visual acuity. It was found that center-distance multifocal contact lens designs that are increasingly being prescribed for myopia control reduce distance photopic and mesopic CS in nonpresbyopic patients across a range of spatial frequencies. PURPOSE: This study aimed to determine the effect of center-distance multifocal soft contact lenses (MFCLs) on CS under photopic and mesopic conditions in nonpresbyopic patients. METHODS: Twenty-five myopic, nonpresbyopic adults were fitted binocularly with three lenses: Biofinity single vision contact lens (SVCL), Biofinity Multifocal D +2.50 add, and NaturalVue Multifocal in random order. Contrast sensitivity was measured at distance (4 m) under photopic and mesopic conditions and at near under photopic conditions. Log CS by spatial frequency and area under the log contrast sensitivity function (AULCSF) were analyzed between lenses. RESULTS: Distance photopic CS at each spatial frequency was higher with the SVCL than the MFCLs (P < .001), but there was no difference between the MFCLs (P = .71). Distance mesopic CS from 1.5 to 12 cycles per degree (cpd) was higher with the SVCL than the MFCLs (all P < .02); however, at 18 cpd, there was no difference in CS between NaturalVue and the SVCL (P = .76), possibly because of spurious resolution. Photopic AULCSF for the SVCL was roughly 10% greater than both MFCLs. Contrast sensitivity at near was generally similar between lenses, only slightly lower with the NaturalVue at 11 and 15.5 cpd, but AULCSF at near was not different between lenses (P > .05). CONCLUSIONS: Multifocal contact lenses reduce distance contrast sensitivity under both photopic and mesopic conditions. There is no clinically significant difference in near CS among all three lenses. These data show that MFCLs have effects on vision that are not captured by standard high-contrast visual acuity testing.

The Risks and Benefits of Myopia Control.

PURPOSE: The prevalence of myopia is increasing around the world, stimulating interest in methods to slow its progression. The primary justification for slowing myopia progression is to reduce the risk of vision loss through sight-threatening ocular pathologic features in later life. The article analyzes whether the potential benefits of slowing myopia progression by 1 diopter (D) justify the potential risks associated with treatments. METHODS: First, the known risks associated with various methods of myopia control are summarized, with emphasis on contact lens wear. Based on available data, the risk of visual impairment and predicted years of visual impairment are estimated for a range of incidence levels. Next, the increased risk of potentially sight-threatening conditions associated with different levels of myopia are reviewed. Finally, a model of the risk of visual impairment as a function of myopia level is developed, and the years of visual impairment associated with various levels of myopia and the years of visual impairment that could be prevented with achievable levels of myopia control are estimated. RESULTS: Assuming an incidence of microbial keratitis between 1 and 25 per 10 000 patient-years and that 15% of cases result in vision loss leads to the conclusion that between 38 and 945 patients need to be exposed to 5 years of wear to produce 5 years of vision loss. Each additional 1 D of myopia is associated with a 58%, 20%, 21%, and 30% increase in the risk of myopic maculopathy, open-angle glaucoma, posterior subcapsular cataract, and retinal detachment, respectively. The predicted mean years of visual impairment ranges from 4.42 in a person with myopia of -3 D to 9.56 in a person with myopia of -8 D, and a 1-D reduction would lower these by 0.74 and 1.21 years, respectively. CONCLUSIONS: The potential benefits of myopia control outweigh the risks: the number needed to treat to prevent 5 years of visual impairment is between 4.1 and 6.8, whereas fewer than 1 in 38 will experience a loss of vision as a result of myopia control.

Visual Performance of Center-distance Multifocal Contact Lenses Fit Using a Myopia Control Paradigm.

PURPOSE: The purpose of this study was to examine the visual performance of center-distance MFCLs in nonpresbyopic adults under different illumination and contrast conditions compared with a single-vision contact lens (SVCL). METHODS: Twenty-five adult subjects were fit with three different lenses (CooperVision Biofinity D MFCL +2.50 add, Visioneering Technologies NaturalVue MFCL, CooperVision Biofinity sphere). Acuity and reading performance were evaluated. RESULTS: A statistically significant difference in high-contrast distance acuity was observed (Biofinity, -0.18 ± 0.06; Biofinity MFCL, -0.14 ± 0.08; NaturalVue MFCL, -0.15 ± 0.03; repeated-measures [RM] ANOVA, P = .02). Under mesopic, high-contrast conditions, MFCLs performed worse than SVCLs (Biofinity, -0.05 ± 0.091; Biofinity MFCL, +0.03 ± 0.09; NaturalVue MFCL, +0.05 ± 0.091; RM-ANOVA, P < .0001). Under low-contrast conditions, MFCLs performed one line worse in photopic lighting and two lines worse under mesopic conditions (RM-ANOVA, P < .0001). Glare reduced acuity by 0.5 logMAR for all lenses (RM-ANOVA, P < .001). A statistically significant difference in near acuity was observed (RM-ANOVA, P = .02), but all lenses achieved acuity better than -0.1 logMAR (Biofinity, -0.16 ± 0.06; Biofinity MFCL, -0.17 ± 0.04; NaturalVue MFCL, -0.13 ± 0.08). Reading performance in words per minute (wpm) was worse with MFCLs (Biofinity MFCL, 144 ± 22 wpm; NaturalVue MFCL, 150 ± 28 wpm) than with SVCLs (156 ± 23 wpm; RM-ANOVA, P = .02) regardless of letter size (RM-ANOVA, P = .13). No difference in acuity between the MFCLs was detected (RM-ANOVA: all, P > .05). CONCLUSIONS: Multifocal contact lenses perform similarly to SVCLs for high-contrast targets and display reduced low-contrast acuity and reading speed. Practitioners should recognize that high-contrast acuity alone does not describe MFCL visual performance.

Near visual function measured with a novel tablet application in patients with astigmatism.

CLINICAL RELEVANCE: While the clinical focus of performance metrics is traditionally based on visual acuity, research from the field of visual impairment has demonstrated that metrics such as reading speed and critical print size correlate much more strongly with subjective patient reported outcomes and assessed ability in real-world tasks. BACKGROUND: More recently, digital device use has increasingly replaced many paper-based tasks. Therefore, this study aimed to assess the correlation between standard acuity/contrast metrics and functional reading ability compared to real-world performance on an iPad-based reading task with astigmatic patients corrected wearing toric and mean spherical equivalent contact lenses. METHODS: Thirty-four adult participants, with -0.75 to -1.50-D of refractive astigmatism, were enrolled in a double-masked cross-over study and fitted with toric and spherical equivalent contact lenses, in random order. A digital application was developed to assess zoom, contrast modifications, the distance at which the tablet was held, blink rate, and time to complete the reading task. High and low contrast near logMAR visual acuity were measured along with reading performance (critical print size and optimal reading speed). RESULTS: The amount participants chose to increase tablet font size (zoom) was correlated with their high-contrast visual acuity with toric correction (r = 0.434, p = 0.010). With best sphere correction, zoom was associated with reading speed (r = -0.450, p = 0.008) and working distance (r = 0.522, p = 0.002). Text zoom was also associated with horizontal (toric: r = 0.898, p < 0.001; sphere: r = 0.880, p < 0.001) and vertical scrolling (toric: r = 0.857, p < 0.001; sphere: r = 0.846, p < 0.001). There was a significant negative association between the selection of text contrast and zoom (toric: r = -0.417, p = 0.0141; sphere: r = -0.385, p = 0.025). CONCLUSION: Real-world task performance allows more robust assessment of visual function than standard visual metrics alone. Digital technology offers the opportunity to better understand the impact of different vision correction options on real-world task performance.

Power profiles of centre-distance multifocal soft contact lenses.

PURPOSE: Centre-distance multifocal contact lenses (MFCLs) for myopia control are thought to slow myopia progression by providing both clear foveal vision and myopic defocus. Characterising the power profile of lenses is important to understanding their possible effects on retinal defocus when worn. The power profiles of three commercially available MFCLs were determined. METHODS: Three centre-distance MFCL designs were studied: Biofinity Multifocal D +2.50 add (comfilcon A), Proclear Multifocal D +2.50 add (omafilcon A), and NaturalVue Multifocal (etafilcon A). Two lenses each in power from -1.00D to -6.00D in 1D steps were stored in ISO 18369-3:2017 standard phosphate buffered saline for 24 h. Optical power profiles were measured in a wet cell with the SHSOphthalmic profiler accounting for centre thickness and manufacturer-reported material refractive index. Sagittal power maps from the SHSOphthalmic were exported, and custom MATLAB code was used to generate power profiles by averaging along the vertical and horizontal meridians. One-way anova with Tukey's HSD post-hoc t-tests were used to analyse maximum add power by lens design. RESULTS: Plus power increased out from the lens centre for all three MFCLs. Power profiles of Biofinity D and Proclear D MFCLs show three distinct areas within the optic zone; the distance zone (from lens centre to about 1.6 mm radius), intermediate zone (about 1.6 mm radius to 2.1 mm) and near zone (about 2 mm radius to 4 mm). For NaturalVue MFCLs, plus power starts increasing almost immediately from the lens centre, reaching maximum measured mean plus power at a radius of 2.7 mm. From 2.7 mm to 3.0 mm, there was a decrease in plus power, which was then generally maintained out to the optic zone edge. Across all lens powers, maximum add power was highest with the NaturalVue MFCL (+3.32 ± 0.44D), then Proclear D (+1.84 ± 0.28D) and Biofinity D (+1.47 ± 0.34D) MFCLs (all p < 0.04). Add power peaked at different locations for different lens powers and designs. CONCLUSIONS: Power profiles of MFCLs vary based on lens design and power. These power profiles are consistent with reported myopic and hyperopic changes in peripheral refraction with MFCLs and provide some explanation for reported differences in peripheral refraction with these MFCLs. Further work is needed to determine whether these power profile differences influence myopia progression.

Randomized Clinical Trial of Near Visual Performance with Digital Devices Using Spherical and Toric Contact Lenses.

SIGNIFICANCE: Visual demands today incorporate a significant amount of time using digital devices. Results of this randomized crossover study of spherical and toric contact lenses demonstrated that participants were able to read smaller print size more comfortably and preferred toric contact lenses when using digital devices. PURPOSE: The purpose of this study was to assess how toric contact lens correction affects subjective and objective outcomes of astigmatic patients using real-world digital devices. METHODS: Adult participants, aged between 20 and 38 years with -0.75 to -1.50 D of astigmatism were enrolled in this double-masked randomized crossover 10-day study of Alcon Dailies Aqua Comfort Plus Sphere and Toric (Alcon, Geneva, Switzerland) contact lenses. Electronic high- and low-contrast near logMAR visual acuity and contrast sensitivity were tested. Reading performance was assessed using custom iPad applications; one used a reading sentences test, whereas the other analyzed zoom, contrast, and distance with website-based articles. Participants completed the Near Activity Visual Questionnaire and stated their preferred contact lens correction. RESULTS: Thirty seven participants were screened, 35 participants were enrolled, and 34 participants completed the study. Toric lens correction improved near high- and low-contrast visual acuity by 0.5 to 1 full line (P < .0001) and allowed participants to read one line smaller text on the iPad (P = .01). Participants increased the zoom 11% (P = .004) and the contrast 4% (P = .006) more with spherical lenses while reading articles. Participants held the iPad at approximately the same distance, about 33 cm (P = .63). Eighty five percent of participants preferred the toric correction (P < .0001). Participants reported improved satisfaction with toric lens correction (P = .0002) and noticed the most benefit with tasks such as reading small print and labels/instructions. CONCLUSIONS: This study used digital devices to demonstrate realistic benefits of toric contact lens designs for astigmatic patients.

Comparison of subjective grading of lid wiper epitheliopathy with a semi-objective method.

PURPOSE: To validate a semi-objective method of grading lid wiper epitheliopathy (LWE) compared to subjective assessment. METHODS: Twenty upper and 20 lower eyelid margins of patients with LWE were photographed after instillation of fluorescein and lissamine green. The images were graded by two observers using a 0-3 grading scale for height (%) and width (mm) of the lid staining. The images were also processed using custom designed software in MATLAB. After manual delineation of the staining area, width and perpendicular height were automatically measured throughout the selected area. The height as a proportion of the lid margin width and width measures were then categorized into the same bins as in the grading scale. RESULTS: Repeatability of the image analysis system showed a mean difference (95% limits of agreement) between repeats of -0.01mm (0.03 and -0.05mm) for LWE height, 0.04mm (1.16 and -1.08mm) for LWE width, and -0.11mm2 (0.32 and -0.53mm2) for LWE area. The mean difference (95% limits of agreement) between image analysis and human grading for LWE height was -0.84 grades (0.54 and -2.21 grades), for LWE width was 0.31 grades (1.22 and -0.59 grades), and for the final grade (mean height and width) was -0.26 (0.44 and -0.96 grades) (all p<0.001). CONCLUSION: Human observers tend to overestimate the height and underestimate the width of LWE staining. Lid wiper region is not well defined, thus, it might be a difficult process for human observers to judge the stained region as a proportion of the lid wiper total region.

Vision-guided ocular growth in a mutant chicken model with diminished visual acuity.

Visual experience is known to guide ocular growth. We tested the hypothesis that vision-guided ocular growth is disrupted in a model system with diminished visual acuity. We examine whether ocular elongation is influenced by form-deprivation (FD) and lens-imposed defocus in the Retinopathy, Globe Enlarged (RGE) chicken. Young RGE chicks have poor visual acuity, without significant retinal pathology, resulting from a mutation in guanine nucleotide-binding protein ß3 (GNB3), also known as transducin ß3 or Gß3. The mutation in GNB3 destabilizes the protein and causes a loss of Gß3 from photoreceptors and ON-bipolar cells (Ritchey et al., 2010). FD increased ocular elongation in RGE eyes in a manner similar to that seen in wild-type (WT) eyes. By comparison, the excessive ocular elongation that results from hyperopic defocus was increased, whereas myopic defocus failed to significantly decrease ocular elongation in RGE eyes. Brief daily periods of unrestricted vision interrupting FD prevented ocular elongation in RGE chicks in a manner similar to that seen in WT chicks. Glucagonergic amacrine cells differentially expressed the immediate early gene Egr1 in response to growth-guiding stimuli in RGE retinas, but the defocus-dependent up-regulation of Egr1 was lesser in RGE retinas compared to that of WT retinas. We conclude that high visual acuity, and the retinal signaling mediated by Gß3, is not required for emmetropization and the excessive ocular elongation caused by FD and hyperopic defocus. However, the loss of acuity and Gß3 from RGE retinas causes enhanced responses to hyperopic defocus and diminished responses to myopic defocus.

The combination of IGF1 and FGF2 and the induction of excessive ocular growth and extreme myopia.

Different growth factors have been shown to influence the development of form-deprivation myopia and lens-induced ametropias. However, growth factors have relatively little effect on the growth of eyes with unrestricted vision. We investigate whether the combination of insulin-like growth factor 1 (IGF1) and fibroblast growth factor 2 (FGF2) influence ocular growth in eyes with unrestricted vision. Different doses of IGF1 and FGF2 were injected into the vitreous chamber of postnatal chicks. Measurements of ocular dimensions and intraocular pressure (IOP) were made during and at the completion of different treatment paradigms. Histological and immunocytochemical analyses were performed to assess cell death, cellular proliferation and integrity of ocular tissues. Treated eyes had significant increases in equatorial diameter and vitreous chamber depth. With significant variability between individuals, IGF1/FGF2-treatment caused hypertrophy of lens and ciliary epithelia, lens thickness was increased, and anterior chamber depth was decreased. Treated eyes developed myopia, in excess of 15 diopters of refractive error. Shortly after treatment, eyes had increased intraocular pressure (IOP), which was increased in a dose-dependent manner. Seven days after treatment with IGF1 and FGF2 changes to anterior chamber depth, lens thickness and elevated IOP were reduced, whereas increases in the vitreous chamber were persistent. Some damage to ganglion cells was detected in peripheral regions of the retina at 7 days after treatment. We conclude that the extreme myopia in IGF1/FGF2-treated eyes results from increased vitreous chamber depth, decreased anterior chamber depth, and changes in the lens. We propose that factor-induced ocular enlargement and myopia result from changes to the sclera, lens and anterior chamber depth.

The chicken cornea as a model of wound healing and neuronal re-innervation.

PURPOSE: The cornea is the major refractive component of the eye and serves as a barrier to the external environment. Understanding how the cornea responds to injury is important to developing therapies to treat vision disorders that affect the integrity and refractive properties of the cornea. Thus, investigation of the wound healing responses of the cornea to injury in a cost-effective animal model is a valuable tool for research. This study characterizes the wound healing responses in the corneas of White Leghorn chicken. METHODS: Linear corneal wounds were induced in post-natal day 7 (P7) chicks and cellular proliferation, apoptosis and regulation of structural proteins were assessed using immunohistochemical techniques. We describe the time course of increased expression of different scar-related markers, including vimentin, vinculin, perlecan and smooth muscle actin. RESULTS: We find evidence for acute necrotic cell death in the corneal region immediately surrounding cite of incision, whereas we failed to find evidence of delayed cell death or apoptosis. We find that the neuronal re-innervation of SV2-positive axon terminals within the corneal stroma and epithelium occurs very quickly after the initial scarring insult. We describe an accumulation of cells within the stroma immediately underlying the scar, which results, at least in part, from the local proliferation of keratocytes. Further, we provide evidence for scar-induced accumulations of CD45-positive monocytes in injured corneas. CONCLUSIONS: We conclude that the chick cornea is an excellent model system in which to study wound healing, formation of scar tissue, and neuronal re-innervation of sensory endings.

Mitogen-activated protein kinase-signaling regulates the ability of Müller glia to proliferate and protect retinal neurons against excitotoxicity.

The purpose of this study was to investigate whether insulin, fibroblast growth factor (FGF), and mitogen-activated protein kinase (MAPK) pathways protect retinal neurons against excitotoxicity and regulate the proliferation of Müller glia. We found that intraocular injections of insulin or FGF2 had variable effects upon the phosphorylation of ERK1/2, p38 MAPK, and CREB, and the expression of immediate early genes, cFos and Egr1. Accumulations of pERK1/2, p38 MAPK, pCREB, cFos and Egr1 in response to insulin or FGF2 were confined to Müller glia, whereas retinal neurons did not seem to respond to growth factors. Unlike FGF2, insulin stimulated microglia-like cells to upregulate the intermediate filament transitin and lysosomal membrane glycoprotein (LMG). With microglia-like cells and Müller glia stimulated by insulin or FGF2 there were profound effects upon numbers of dying neurons in response to excitotoxic damage. Although FGF2 significantly reduced numbers of dying neurons, insulin significantly increased numbers of dying neurons. In addition to neuroprotective affects, FGF2 also "primed" the Müller glia to proliferate following retinal damage, whereas insulin had no effect upon glial proliferation. Further, we found that FGF receptor isoform 1 (FGFR1) and FGFR3 were prominently expressed in the retina, whereas the insulin receptor and FGFR2 are not expressed, or are expressed at very low levels. We conclude that MAPK-signaling through FGF receptors stimulates Müller glia to become more neuroprotective and progenitor-like, whereas insulin acting on Müller and microglia-like cells through unidentified receptors had the opposite effect.

Bullwhip neurons in the retina regulate the size and shape of the eye.

Bullwhip and mini-bullwhip cells are unconventional types of retinal neurons that utilize the neuropeptides glucagon, glucagon-like peptide 1 (GLP1) and substance P. These cells have been implicated in regulating the proliferation of neural progenitors in the circumferential marginal zone (CMZ) of the chicken retina. The purpose of this study was to investigate the roles of the bullwhip cells in regulating ocular size and shape. We found that intravitreal delivery of colchicine at postnatal day 7 destroys the vast majority (approximately 98%) of the bullwhip and mini-bullwhip cells and their peptidergic terminals that are concentrated in the CMZ near the equator of the eye. Interestingly, colchicine-treatment resulted in excessive ocular growth that involved the expansion of equatorial diameter, but not axial length. Intraocular injections of glucagon completely prevented the equatorial expansion that occurs with colchicine-treatment. In eyes with undamaged retinas, exogenous glucagon suppressed equatorial eye growth, whereas glucagon receptor antagonists caused excessive equatorial growth. Furthermore, visual stimuli that increase or decrease rates of ocular growth caused a down- or up-regulation, respectively, of the immediate early gene Egr1 in the bullwhip cells; indicating that the activity of the bullwhip cells is regulated by growth-guiding visual cues. We found that the glucagon receptor was expressed by cells in the fibrous and cartilaginous sclera in equatorial regions of the eye. Taken together, these findings suggest that glucagon peptide released from the terminals of the bullwhip and mini-bullwhip cells regulates the growth of the equatorial sclera in a vision-dependent manner. Although the bullwhip and mini-bullwhip cells are not abundant, less than 1000 cells per retina, their influence on the development of the eye is substantial and includes vision-guided ocular growth.

The comparison of overnight lens modalities (COLM) study.

PURPOSE: The Comparison of Overnight Lens Modalities (COLM) Study is a controlled, randomized, clinical pilot study to determine the sample size required to perform a multicenter clinical trial comparing Paragon CRT lenses with CIBA Vision Focus NIGHT and DAY 30-day continuous-wear silicone hydrogel lenses. METHODS: Twenty subjects were enrolled in the study. Eighteen subjects, 8 CRT and 10 Focus NIGHT and DAY lens wearers, completed the 3-month study. Visual acuity and refractive quality of life were assessed. Nonparametric statistics were used to analyze differences within and between treatment groups for refraction, visual acuity, and refractive quality of life. The Wilcoxon rank sum test was used to analyze differences between the groups in refraction, visual acuity, and refractive quality of life. The Wilcoxon signed rank test was also used to monitor changes in refraction, refractive quality of life, and visual acuity within a group. Sample size calculations were performed to determine the sample size needed for a large-scale clinical trial. RESULTS: No statistically significant difference was observed between the groups for 12 of 13 scales on the National Eye Institute Refractive Error Quality of Life Instrument (NEI RQL-42) after treatment. A statistically significant difference was observed between the CRT and Focus NIGHT and DAY groups after 3 months for the NEI RQL-42 dependence-on-correction scale (P=0.0032). There was a significant change within the CRT group between baseline and 3 months (P=0.0156). No statistically significant difference was observed between the two groups in Bailey-Lovie high- and low-contrast visual acuity after 3 months. CONCLUSIONS: The NEI RQL-42 may be able to detect differences in refractive quality of life between two contact lens treatment groups for the dependence-on-correction scale. Paragon CRT and CIBA Vision Focus NIGHT and DAY lenses produced similar high- and low-contrast visual acuity in this study. A sample size of 126 subjects per group is required to find a 10-unit difference on the NEI RQL-42.