REGIONAL VARIATION IN FLUID RESERVOIR THICKNESS, OXYGEN TRANSMISSIBILITY AND CORNEAL OEDEMA DURING SCLERAL LENS WEAR

Purpose: To determine if regional variation in post lens fluid reservoir thickness (PLFT) during scleral lens wear leads to regional variation in oxygen transmissibility and corneal edema during 4 hours of non-fenestrated scleral lens wear.Methods: About 20 healthy subjects (mean age, 28.8 ± 4.2 years) were fitted with nonfenestrated rotationally symmetric scleral lenses. Anterior segment optical coherence tomography was used to measure cornea thickness before and after lens wear, PLFT 10 minutes and 4 hours after lens application, and scleral lens thickness (with the scleral lens in situ) 4 hours after scleral lens application. These measurements were limited to the central 6 mm and divided into three zones (central, mid-peripheral, and peripheral zones). In the mid-peripheral and peripheral zones, eight principal meridians were measured, generating 17 measurement points in total. Scleral lens thickness and PLFT measurements were corrected for optical distortions by a series of equations. Oxygen transmissibility was calculated by dividing the scleral lens oxygen permeability by the optically-corrected scleral lens thickness, taking into account the oxygen permeability of saline and fluid reservoir thickness.Results: A significant regional variation in PLFT (F = 12.860, P = 0. 012) was observed after 10 minutes of the lens application, PLFT was thickest and thinnest in the inferotemporal and the superonasal region of the peripheral zones( 322.6 ± 161.8 µm and 153.8 ± 96.4 µm, respectively); however, this variation was not statistically significant at 4 hours of scleral lens wear (F = 4.692; P = 0.073). Despite significant regional variation in oxygen transmissibility (F = 48.472; P = 0.001) and relatively low oxygen transmissibility through the scleral lens, induced corneal edema did not vary significantly in different regions (F = 3.346; P = 0.126). In the central corneal region, the induced corneal edema correlated moderately with PLFT (r = 0.468; P = 0.037) and oxygen transmissibility (r = -0.528; P = 0.017). This relationship was insignificant in the peripheral cornea.Conclusion: The inferotemporal peripheral region had the thickest PLFT and least oxygen transmissibility, and the superonasal region had the vice versa. Despite significant variation in PLFT and oxygen transmissibility initially, in healthy corneas, this variation does not seem to induce statistically significant regional variation in corneal edema. Increased central PLFT and decreased oxygen transmissibility moderately correlate with central corneal edema.

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Fluid Reservoir Thickness and Corneal Edema during Open-eye Scleral Lens Wear

Optometry and Vision Science ◽

10.1097/opx.0000000000001558 ◽

2020 ◽

Vol 97 (9) ◽

pp. 683-689 ◽

Cited By ~ 5

Author(s):

Damien Fisher ◽

Michael J. Collins ◽

Stephen J. Vincent

Keyword(s):

Corneal Edema ◽

Lens Wear ◽

Fluid Reservoir

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Study of Myopia Correction Using Nanoporous Polymer Gas Permeable Contact Lenses

Materiale Plastice ◽

10.37358/mp.21.4.5531 ◽

2022 ◽

Vol 58 (4) ◽

pp. 55-64

Author(s):

Silvia Salavastru ◽

Irina Andreea Niagu ◽

Luana Andrei Macovei ◽

Lucretia Anghel ◽

Nicolae Sarbu ◽

...

Keyword(s):

Contact Lens ◽

Contact Lenses ◽

Anterior Segment ◽

Silicone Hydrogel ◽

Before And After ◽

Materials Used ◽

Ocular Comfort ◽

Myopic Astigmatism ◽

Lens Wear

Ophthalmic treatments using contact lenses are now used by more and more specialists around the world. Improving contact lens (CL) materials is a condition that is constantly evolving. Contact lens materials are usually composed of polymer hydrogel or silicone hydrogel. The materials used for night contact lenses are gas permeable and they gradual flatten the center of the cornea which decreases the progression of myopia or myopic astigmatism. The aim of this study is to identify, in correlation with the chemical interactions between structural components of contact lenses and their biocompatibility with the surface layer and microtopography of the cornea or sclera, different incidents that occur in patients who have used rigid gas permeable contact lenses. The study was performed on a group of 10 patients who had a follow-up period between 4 and 6 years, who presented regularly for eye examinations. The following clinical parameters were analyzed: ocular refraction before and after wearing night contact lenses, types of contact lens materials, appearance of corneal topography, biomicroscopic examination of the anterior segment of the eye, keratometry, ocular comfort, as well as other incidents regarding this type of lenses. Difficulties caused by wearing contact lenses at night arose due to poor hygiene and maintenance in two cases or due to interruption of lens wear in one case.

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Responses of the Ocular Anterior Segment and Refraction to 0.5% Tropicamide in Chinese School-Aged Children of Myopia, Emmetropia, and Hyperopia

Journal of Ophthalmology ◽

10.1155/2015/612728 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 4

Author(s):

Ying Yuan ◽

Zhengwei Zhang ◽

Jianfeng Zhu ◽

Xiangui He ◽

Ergang Du ◽

...

Keyword(s):

Anterior Chamber ◽

Anterior Segment ◽

Anterior Chamber Depth ◽

School Aged Children ◽

Lens Thickness ◽

Lens Position ◽

Before And After ◽

Chinese School ◽

The Relationship ◽

Parameters Of Interest

Purpose. To investigate the changes of anterior segment after cycloplegia and estimate the association of such changes with the changes of refraction in Chinese school-aged children of myopia, emmetropia, and hyperopia.Methods. 309 children were recruited and eligible subjects were assigned to three groups: hyperopia, emmetropia, or myopia. Cycloplegia was achieved with five cycles of 0.5% tropicamide. The Pentacam system was used to measure the parameters of interest before and after cycloplegia.Results. In the myopic group, the lenses were thinner and the lens position was significantly more posterior than that of the emmetropic and hyperopic groups in the cycloplegic status. The correlations between refraction and lens thickness (age adjusted;r=0.26,P<0.01), and lens position (age adjusted;r=-0.31,P<0.01) were found. After cycloplegia, ACD and ACV significantly increased, while ACA significantly decreased. Changes in refraction, ACD, ACV, and ACA were significantly different among the three groups (P<0.05, all). Changes of refraction were correlated with changes of ACD (r=0.41,P<0.01).Conclusions. Myopia presented thinner lenses and smaller changes of anterior segment and refraction after cycloplegia when compared to emmetropia and hyperopia. Changes of anterior chamber depth were correlated with refraction changes. This may contribute to a better understanding of the relationship between anterior segment and myopia.

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STUDY CLINICAL FEATURE AND RESULT OF TREATMENT PHACOMORPHIC GLAUCOMA

Journal of Medicine and Pharmacy ◽

10.34071/jmp.2015.1.9 ◽

2015 ◽

pp. 71-75

Author(s):

Van Nam Phan ◽

Ba Ken Tran

Keyword(s):

Visual Acuity ◽

Intraocular Pressure ◽

Statistical Significance ◽

Corneal Edema ◽

Clinical Feature ◽

Anterior Chamber Angle ◽

Male Population ◽

Significant Difference ◽

Operative Complications ◽

Before And After

Purpose: Study clinical feature of phacomorphic glaucoma. To evaluate the result of treatment phacomorphic glaucoma. Method: The retrospective, interventional study on 36 cases with phacomorphic glaucoma who underwent treated at Hue Central Hospital from 6/2010 to 6/2011. Standard of research: visual, IOP, before and after surgery, accompanying lesions and post-operative complications. The surgery is considered successful when postoperative IOP less than 21 mmHg. Results: Age 50-59 presented 30.5 percent, ≥ 60 presented 91.7 percent. There was a slight female preponderance (66.7%) compared to the male population (33.3%) which implies a statistically marginally significant difference. However there was no statistical significance difference when compared by the two subgroups. Patient in country presented 61,1% and city presented 38,9%. The duration between the onset of pain and surgery from 0 to < 5 days (77.8%), from 6 to 10 (16.7%) and >10 days presented 5.5%. The preoperative intraocular pressure 35 to 45mmHg (47.2%), 46-55 (30.6%), 56-65 (13.9%) and more than 65 presented 8.3%. The visual acuity preoperation less than 1metre count finger (94.5%), less than 3 metre count finger presented 5.5%. Close anterior chamber angle presented 80.6% and shallow was presented 19.4%. Corneal edema presented 100%, iritis presented 94.4%, dilated pupil larger 5mm presented 83.3%, Synchynea iris and cataract presented 72.2%. ECCE, implantation IOL combined trabeculectomy presented 11.1%, Phaco, implantation IOL combined trabeculectomy presented 69,5%, ECCE implantation IOL presented 5.6%, Phaco, implantation IOL presented 13.8%. Postoperative visual acuity from 1/10 to 5/10 presented 72.2%, no case have VA larger than 5/10. Postoperative 3 months VA 1/10 to 5/10 presented 72.2%, larger VA 5/10 presented 8.3%. Postoperative 3 months intraocular pressure ≤ 21mmHg presented 91.7%, 22 to 24mmHg presented 8.3%, no case have IOP ≥25mmHg. Postoperative edema presented 58.3%, iritis presented 58.3%. Key words: phacomorphic Glaucoma

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Subtle changes of the crystalline lens after cycloplegia: a retrospective study

BMC Ophthalmology ◽

10.1186/s12886-021-01884-9 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Cheng Dai ◽

Meng Liu ◽

Xiaodong Lv ◽

Binzhong Li

Keyword(s):

Retrospective Study ◽

Children And Adolescents ◽

Population Change ◽

Anterior Segment ◽

Anterior Chamber Depth ◽

Crystalline Lens ◽

Equivalent Diameter ◽

Crystalline Morphology ◽

Significant Difference ◽

Before And After

Abstract Background The purpose of this study was to evaluate the shape of the crystalline lens in terms of biometry and diopters before and after cycloplegia using the CASIA2 swept-source (SS) optical coherence tomography (OCT) system on the anterior segment. Methods This was a retrospective study. Children and adolescents (26 males and 29 females, aged 4–21 years) with simple ametropia were selected for optometry and CASIA2 imaging at 2 separate visits before and after cycloplegia. Diopter values were derived from the spherical power (S) obtained by optometry. Biometric parameters of the crystalline lens, including the anterior chamber depth (ACD), anterior and posterior curvature of the lens (ACL and PCL), lens thickness (LTH), lens decentration (LD), lens tilt (LT), and equivalent diameter of the lens (LED), were measured by the CASIA2 system. The differences in these parameters after compared with before cycloplegia were determined, and their relationships were analyzed. Results Fifty-five participants (106 eyes) were initially enrolled. There was a significant difference (P < 0.05) in the S (t=-7.026, P < 0.001), ACD (t=-8.796, P < 0.001), ACL (t=-13.263, P < 0.001) and LTH (t = 7.363, P < 0.001) after compared with before cycloplegia. The change in the PCL (t = 1.557, P = 0.122), LD (t = 0.876, P = 0.383), LT (t = 0.440, P = 0.661) and LED (t=-0.351, P = 0.726) was not statistically significant (P > 0.05). There was a significant (P < 0.05) correlation of the change in the S with that in the ACL (r = 0.466, P < 0.001), LTH (r=-0.592, P < 0.001), and LED (r = 0.223, P = 0.021) but not the PCL (r = 0.19, P = 0.051), LD (r=-0.048, P = 0.0628) or LT (r=-0.022, P = 0.822). Furthermore, the change in the ACD was closely related to the change in crystalline morphology. However, in children and adolescents, we found that the change in crystalline morphology was unrelated to age. Conclusions Changes in lens morphology after compared with before cycloplegia are mainly related to the ACL and LTH, but there is no difference in the PCL, LD, LT, or LED. In the adolescent population, change in the S is related to change in the ACL, LED and LTH. However, age is unrelated to the shape and tendency of the crystalline lens. Further research is required to determine whether the same conclusion applies to different age groups and different refractive states (myopia, hyperopia, emmetropia) .

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Intermittent corneal edema due to anterior segment retained lens fragments

Journal of Cataract & Refractive Surgery ◽

10.1016/j.jcrs.2007.02.036 ◽

2007 ◽

Vol 33 (6) ◽

pp. 1136-1137 ◽

Cited By ~ 1

Author(s):

Ahmet T. Yazıcı ◽

Vedat Kaya ◽

Ercument Bozkurt ◽

Serhat Imamoglu ◽

Omer F. Yılmaz

Keyword(s):

Anterior Segment ◽

Corneal Edema

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Impact of freeze-thaw cytoablation on aqueous outflow patterns in ex vivo anterior chamber perfusion cultures and whole eyes

F1000Research ◽

10.12688/f1000research.53572.1 ◽

2021 ◽

Vol 10 ◽

pp. 525

Author(s):

Raoul Verma-Fuehring ◽

Mohamad Dakroub ◽

Alicja Strzalkowska ◽

Piotr Strzalkowski ◽

Hong Han ◽

...

Keyword(s):

Trabecular Meshwork ◽

Structural Changes ◽

Ex Vivo ◽

Anterior Segment ◽

Large Change ◽

Invasive Technique ◽

Freeze Thaw ◽

Before And After ◽

Human Eyes ◽

Porcine Eyes

Background: Porcine eyes have been widely used as ex vivo models in glaucoma research, as they share similar features with human eyes. Freeze-thawing is a non-invasive technique that has been used to obliterate living cells in anterior segment ex vivo cultures, to prepare them for further research such as cellular repopulation. This technique has previously been shown to reduce the intraocular pressure (IOP) in porcine eyes. The aim of this study was to investigate whether freeze-thaw cytoablation causes corresponding canalogram outflow changes in perfused anterior segment cultures (AFT) and whole porcine eyes (WFT). We hypothesized that the known IOP drop in AFT after trabecular meshwork ablation by freeze-thaw would be accompanied by a similarly large change in the distal outflow pattern. Methods: Two-dye (fluorescein and Texas red) reperfusion canalograms were used to compare the outflow time before and after two -80°C cycles of freeze-thaw. We assigned 28 freshly enucleated porcine eyes to four groups: perfused anterior segment dye controls (ACO, n = 6), perfused whole eye dye controls (WCO, n = 6), freeze-thaw treated anterior segment cultures (AFT, n = 10), and freeze-thaw treated whole eyes (WFT, n = 6). Results: In control groups ACO and WCO, the two different dyes had similar filling times. In AFT, the outflow pattern and filling times were unchanged. In WFT, the temporal superior quadrant filled more slowly (p = 0.042) while all others remained unchanged. The qualitative appearance of distal outflow spaces was altered only in some eyes. Conclusions: Freeze-thaw cytoablation caused neither loss nor leakage of distal outflow structures. Surprisingly, the loss of an intact trabecular meshwork over the entire circumference did not result in a general acceleration of quadrant outflow times. The results validate freeze-thawing as a method to generate an extracellular matrix without major structural changes.

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Morphological changes in the trabecular meshwork and Schlemm’s canal after treatment with topical intraocular pressure-lowering agents

Scientific Reports ◽

10.1038/s41598-021-97746-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ji-Hye Park ◽

Hyun Woo Chung ◽

Eun Gyu Yoon ◽

Min Jung Ji ◽

Chungkwon Yoo ◽

...

Keyword(s):

Intraocular Pressure ◽

Trabecular Meshwork ◽

Morphological Changes ◽

Open Angle Glaucoma ◽

Anterior Segment ◽

Schlemm’S Canal ◽

Schlemm's Canal ◽

Before And After ◽

Treatment Naïve ◽

Aqueous Outflow

AbstractGlaucoma treatment is usually initiated with topical medication that lowers the intraocular pressure (IOP) by reducing the aqueous production, enhancing the aqueous outflow, or both. However, the effect of topical IOP-lowering medications on the microstructures of the aqueous outflow pathway are relatively unknown. In this retrospective, observational study, 56 treatment-naïve patients with primary open-angle glaucoma were enrolled. Images of the nasal and temporal corneoscleral limbus were obtained using anterior segment optical coherence tomography (AS-OCT). The conjunctival vessels and iris anatomy were used as landmarks to select the same limbal area scan, and the trabecular meshwork (TM) width, TM thickness, and Schlemm’s canal (SC) area were measured before and after using the IOP-lowering agents for 3 months. Among the 56 patients enrolled, 33 patients used prostaglandin (PG) analogues, and 23 patients used dorzolamide/timolol fixed combination (DTFC). After 3 months of DTFC usage, the TM width, TM thickness, and SC area did not show significant changes in either the nasal or temporal sectors. Conversely, after prostaglandin analog usage, the TM thickness significantly increased, and the SC area significantly decreased (all P < 0.01). These findings warrant a deeper investigation into their relationship to aqueous outflow through the conventional and unconventional outflow pathways after treatment with PG analogues.

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Age-Related Changes in the Rhesus Macaque Eye

10.1101/2021.07.14.452427 ◽

2021 ◽

Author(s):

Kira Lin ◽

Tu Tran ◽

Soohyun Kim ◽

Sangwan Park ◽

Jiajia Chen ◽

...

Keyword(s):

Optical Coherence Tomography ◽

Intraocular Pressure ◽

Rhesus Macaque ◽

Axial Length ◽

Rhesus Macaques ◽

Anterior Segment ◽

Optical Coherence ◽

Lens Thickness ◽

Age Related ◽

Age Related Changes

Purpose: To assess age-related changes in the rhesus macaque eye and evaluate them to corresponding human age-related eye disease. Methods: Data from eye exams and imaging tests including intraocular pressure (IOP), lens thickness, axial length, and retinal optical coherence tomography (OCT) images were evaluated from 142 individuals and statistically analyzed for age-related changes. Quantitative autofluorescence (qAF) was measured as was the presence of macular lesions as related to age. Results: Ages of the 142 rhesus macaques ranged from 0.7 to 29 years (mean=16.4 years, stdev=7.5 years). Anterior segment measurements such as IOP, lens thickness, and axial length were acquired. Advanced retinal imaging in the form of optical coherence tomography and qAF were obtained. Quantitative assessments were made and variations by age groups were analyzed to compare with established age-related changes in human eyes. Quantitative analysis of data revealed age-related increase in intraocular pressure, ocular biometry (lens thickness and axial length), and presence of macular lesions. Age-related changes in thicknesses of retinal layers on OCT were observed and quantified. Age was correlated with increased qAF. Conclusions: The rhesus macaque has age-related ocular changes similar to humans. IOP increases with age while retinal ganglion cell layer thickness decreases. Macular lesions develop in some aged animals. Our findings support the concept that rhesus macaques may be useful for the study of important age-related diseases such as glaucoma, macular diseases, and cone disorders, and for development of therapies for these diseases.

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HYDROGELS FROM POLYACRYLIC ACID FOR REDUCTION OF BIOADHESION ON SILICONE CONTACT LENSES

Contemporary Materials ◽

10.7251/comen1401095a ◽

2014 ◽

Vol 5 (1) ◽

Author(s):

Zahida Ademović ◽

Snježana Marić ◽

Peter Kingshott ◽

Zoran Iličković

Keyword(s):

Surface Modification ◽

Oxygen Permeability ◽

Contact Lenses ◽

Low Oxygen ◽

Maldi Tof Ms ◽

Maldi Tof ◽

Angle Measurements ◽

Contact Angle Measurements ◽

Lysozyme Adsorption ◽

Tof Ms

Contact lenses suffer from two limitations: low oxygen permeability and deposition of protein and lipids. In order to prevent bioadhesion, surface must be completely inert to all biological reactions. To achieve this, surface properties must be tailored. Also, to improve comfort, surface must be highly wettable and lubricous. In this paper the surface of silicone contact lenses was modified by plasma induced copolymerization of acrylic acid. A wettable surface was generated and in addition carboxyl groups that were created on the surface provided an ideal reactive platform for subsequent grafting of polyethylene glycol. Each surface modification step was analysed by XPS and contact angle measurements. Lysozyme adsorption on modified silicone contact lenses was analysed by surface-MALDI-ToF-MS and XPS. After incubation with lysozyme, surface-MALDI-TOF-MS and XPS analysis showed a reduction of adsorbed lysozyme on hydrogel modified contact lenses. Surface modification of silicone with PEG is a method for reduction of protein adsorption on contact lenses.

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