Molecular mechanism of hypoxia and alpha-ketoglutaric acid on collagen expression in scleral fibroblasts

AIM:To investigate the molecular mechanisms underlying the influence of hypoxia and alpha-ketoglutaric acid(α-KG)on scleral collagen expression.METHODS:Meta-analysis and clinical statistics were used to prove the changes in choroidal thickness(ChT)during myopia.The establishment of a hypoxic myopia model(HYP)for rabbit scleral fibroblasts through hypoxic culture and the effects of hypoxia andα-KG on collagen expression were demonstrated by Sirius red staining.Transcriptome analysis was used to verify the genes and pathways that hypoxia andα-KG affect collagen expression.Finally,real-time quantitative reverse transcription polymerase chain reaction(RT-qPCR)was used for reverse verification.RESULTS:Meta-analysis results aligned with clinical statistics,revealing a thinning of ChT,leading to scleral hypoxia.Sirius red staining indicated lower collagen expression in the HYP group and higher collagen expression in the HYP+α-KG group,showed that hypoxia reduced collagen expression in scleral fibroblasts,whileα-KG can elevated collagen expression under HYP conditions.Transcriptome analysis unveiled the related genes and signaling pathways of hypoxia andα-KG affect scleral collagen expression and the results were verified by RT-qPCR.CONCLUSION:The potential molecular mechanisms through which hypoxia andα-KG influencing myopia is unraveled and three novel genes TLCD4,TBC1D4,and EPHX3 are identified.These findings provide a new perspective on the prevention and treatment of myopia via regulating collagen expression.

Advances in the treatment of rhegmatogenous retinal detachment

The pathogenesis of rhegmatogenous retinal detachment depends on three factors, namely, retinal rupture, vitreous liquefaction and traction causing the retina to separate from the pigment epithelium, among which retinal rupture is the most important. Retinopathy is caused by a gap between the neurosensory retina and the retinal pigment epithelium, which severely damages the visual function of the patient. Therefore, early clinical discovery, prevention and selection of an appropriate treatment are important. This article reviews progress in the treatment of retinal detachment.

Expression and role of specificity protein 1 in the sclera remodeling of experimental myopia in guinea pigs

AIM：To study the expression of collagen I and transcription factor specificity protein 1（Sp1）,a transforming growth factor-β1（TGF-β1） downstream target,and reveal the impact of the TGF-β1-Sp1 signaling pathway on collagen remodeling in myopic sclera.METHODS：Seventy-five 1-week-old guinea pigs were randomly divided into normal control,form deprivation myopia（FDM）,and self-control groups.FDM was induced for different times using coverage with translucent latex balloons and FDM recovery was performed for 1wk after 4wk treatment;then,changes in refractive power and axial length were measured.Immunohistochemistry and reverse transcription-polymerase chain reaction were used to evaluate dynamic changes in collagen I and Sp1 expression in the sclera of guinea pigs with emmetropia and experimental myopia,and the relationship between collagen I and Sp1 levels was analyzed.RESULTS：In the FDM group,the refractive power was gradually changed（from 2.09±0.30 D at week 0 to-1.23±0.69 D,-4.17±0.59 D,-7.07±0.56 D,and-4.30±0.58 D at weeks 2,4,6,and 1wk after 4wk,respectively;P〈0.05）,indicating deepening of myopia.The axial length was increased（from 5.92±0.39 mm at week 0 to 6.62±0.36 mm,7.30±0.34 mm,7.99±0.32 mm,and 7.41±0.36 mm at weeks 2,4,6,and 1wk after 4wk;P〈0.05）.The m RNA and protein expression of Sp1 and collagen I in the sclera of the FDM group was lower than that of the control groups（P〈0.05）,and the reduction was eye-coverage time-dependent.Furthermore,correlation between Sp1 and collagen I down-regulation in the myopic sclera was observed.CONCLUSION：Our data indicate that transcription factor Sp1 may be involved in the regulation of type I collagensynthesis/degradation during myopic sclera remodeling,suggesting that TGF-β1 signaling plays a role in the development and progression of myopia.

Form-deprivation myopia induces decreased expression of bone morphogenetic protein-2, 5 in guinea pig sclera

AIM: To identify the presence of various bone morphogenetic proteins(BMPs) and their receptors in normal sclera of human, rat and guinea pigs, and to determine whether their expression changed with form-deprivation myopia(FDM) in guinea pig sclera.METHODS: The expression of BMPs and BMP receptors were detected using reverse transcription polymerase chain reaction(RT-PCR) and immunofluorescence. Two-week-old guinea pigs were monocularly form-deprived with a translucent lens. After fourteen days induction of FDM, total RNA was isolated and subjected to RT-PCR to examine the changes of BMPs and BMP receptors in tissues from the posterior sclera. Western blotting analysis was used to investigate their changes in protein levels.RESULTS: Human sclera expressed m RNAs for BMP-2,-4,-5,-7,-RIA,-RIB and BMP-RII. Conversely, rat sclera only expressed m RNA for BMP-7 and BMP-RIB,while the expression of BMPs and BMP receptors in guinea pigs were similar to that of humans. Human sclera also expresses BMP-2,-4,-5,-7 in protein level.Fourteen days after the induction of myopia, significant decreased expressions for BMP-2 and BMP-5 in the posterior sclera of FDM-affected eyes(P 【0.05 vs internal control eyes).· CONCLUSION: Various BMPs were expressed in human and guinea pig sclera. In the posterior sclera,expressions of BMP-2 and BMP-5 significantly decreased in FDM eyes. This finding indicates that various BMPs as components of the scleral cytokines regulating tissue homeostasis and provide evidence that alterations in the expression of BMP-2 and BMP-5 are associated with sclera remodeling during myopia induction.

Scleral ultrastructure and biomechanical changes in rabbits after negative lens application

AIM： To address the microstructure and biomechanical changes of the sclera of rabbits after negative lens application by spectacle frame apparatus. METHODS： Five New Zealand rabbits of seven weeks post-natal were treated with -8 D lens monocularly over the course of two weeks. Refractive errors and axial length （AXI.） were measured at the 1st, 7th and 14th days of the induction period. Ultrastructure of sclera was determined with electron microscopy. Biomechanical properties were tested by an Instron 5565 universal testing machine. RESULTS： l.ens-induced （1.1） eyes elongated more rapidly compared with fellow eyes with AXI. values of 15.56±0.14 and 15.21±0.14 mm （P〈0.01）. Fibril diameter was significantly smaller in the I.I eyes compared with control ones in the inner, middle, and outer layers （inner layer, 63.533 vs 76.467 nm; middle layer, 92.647 vs 123.984 nm; outer layer, 86.999 vs 134.257 nm, P〈0.01, respectively）. In comparison with control eyes, macrophage-like cells that engulfed fibroblasts, dilated endoplasmic reticulum, and vacuoles in fibroblasts were observed in the inner and middle stroma in the/U eyes. Ultimate stress and Young＇s modulus were lower in the I.I eyes compared with those in the control eyes. CONCLUSION： Negative lens application alters eye growth, and results in axial elongation with changes in scleral ultrastructural and mechanical properties.

Dynamic changes of activator protein 1 and collagen I expression in the sclera of myopia guinea pigs

AIM: To investigate the dynamic changes of activator protein 1(AP1) and collagen I expression in the sclera of form-deprivation myopic model in guinea pigs. METHODS: A form-deprivation myopic model in guinea pigs were established with the left eye covered for 2 to 6 wk(FDM group). Normal control group(n=25) were untreated. Changes in refractive power and axial length(AL) were measured and recorded at different time points. Expressions of AP1 and collagen 1 of the sclera were measured with Western blotting and reverse transcription-polymerase chain reaction(RT-PCR). The relationship between AP1 and collagen I levels was analyzed. RESULTS: After 0, 2, 4, 6 wk, and 4/-1 wk of form-deprivation, the diopter in the FDM group was gradually changed(2.08±0.31,-1.23±0.68,-4.17±0.58,-7.07±0.55, and-2.67±0.59 D, respectively, P<0.05), and the AL was gradually increased(5.90±0.38, 6.62±0.37, 7.30±0.35, 7.99±0.31, and 6.97±0.32 mm, respectively, P<0.05). With the prolongation of covered time, the protein expressions of AP1 and collagen I in the FDM group were gradually down-regulated(all P<0.05);the mRNA expressions of them were also gradually down-regulated(all P<0.05);and there was positive correlation between them. The control group had no obvious change in each index(all P>0.05). CONCLUSION: AP1 may be an important transcription factor involved in the regulation of collagen I synthesis and degradation during myopic scleral remodeling.

Protective effects of riboflavin-UVA-mediated posterior sclera collagen cross-linking in a guinea pig model of form-deprived myopia

AIM:To evaluate the effect of posterior sclera collagen cross-linking induced by riboflavin-ultraviolet A(UVA)on form-deprived myopia in guinea pigs.METHODES:Twenty-five pigmented guinea pigs of 3-week-old were randomly assigned into 4 groups that included normal control(NOR,n=7),form-deprived(FDM,n=7),normal with riboflavin-UVA cross-linking(NOR+CL,n=5)and form-deprived with cross-linking(FDM+CL,n=6).The NOR+CL group and the FDM+CL group received the riboflavin-UVA induced cross-linking at day 0.FDM was induced by monocularly deprived with facemask in the right eyes.The refraction,axial length and corneal curvature were measured by retinoscopy,A-scan and keratometer respectively in scheduled time points(day 0 and 1,2,3,4 wk after form-deprivation).At the end of 4 weeks’experiment,stress-strain tests of sclera were measured and morphological changes of sclera and retina were examined.RESULTS:After 4 wk,the interocular difference of refractive error were-0.11±0.67,-2.93±0.56,1.10±0.58,and-1.63±0.41 D in the NOR,FDM,NOR+CL,and FDM+CL groups respectively.Mixed-effect linear model revealed significant effect of FDM(P<0.01)and CL(P<0.001).Also,after 4 wk,the interocular difference of axial length were 0.01±0.04,0.29±0.07,-0.13±0.06,and 0.11±0.05 mm in the NOR,FDM,NOR+CL,and FDM+CL group.Mixedeffect linear model revealed significant effect of FDM(P<0.001)and CL(P<0.01).As for corneal curvature,significant interocular difference have not found between any of the two groups.At the end of this experiment,the ultimate stress and elastic modulus were found significantly increased in both CL groups.But no difference was found in the groups without cross-linked.There was no abnormality observed in the retina and RPE cells of the treated eyes.CONCLUSION:The posterior sclera collagen crosslinking induced by riboflavin-UVA can slow down the progress of myopia and increase the sclera biomechanical strength in the guinea pig model of form-deprived myopia.

Complement factors C1q, C3 and C5b-9 in the posterior sclera of guinea pigs with negative lens-defocused myopia

· AIM: To investigate the expression of complement factors in the posterior scleral fibroblasts of guinea pigs with negative lens-defocused myopia.· METHODS: Eighteen guinea pigs were assigned randomly to two groups: the negative lens-defocused group(NLD group, n =9) and the normal control without treatment group(NC group, n =9). The effect of myopic induction was compared in three subgroups: eyes treated with a-10.00 D negative lens in the NLD group(NL group), eyes treated with a plano(0 D) lens in the NLD group(PL group), and untreated right eyes in the NC group(NC group). The following analyses were conducted at four weeks: examination of the refractive error via retinoscopy, assessment of complement C5b-9expression in the posterior scleral fibroblasts using immunohistochemistry, and measurements of complement C1 q and C3 protein levels in the posterior sclera by Western blot.·RESULTS: After an induction period of four weeks, a significant myopic shift was detected in the eyes of the NL group, relative to that of the PL and NC groups(P 【0.05). Data analysis showed a significant increase in the percentage of C5b-9 immunopositive fibroblasts in the posterior sclera of the NL group eyes, compared to the PL group(q =11.50, P 【0.001). Significantly higher levels of C1q(q =4.94, P =0.01) and C3(q =4.07, P =0.03)protein were detected in the posterior sclera of NL group eyes, compared to the PL group. There were no significant difference between the PL and NC groups for C5b-9(q =2.44, P =0.10), C1q(q =1.55, P =0.53) and C3(q =0.98, P =0.77) in the posterior sclera.·CONCLUSION: The data from present study provide evidence of the up-regulation of C5b-9, C1 q and C3 in the posterior scleral fibroblasts in a NLD myopic animal model. The results suggest that the complement system may be involved in the development of myopia.

Regulation of scleral fibroblast differentiation by bone morphogenetic protein-2

Bone morphogenesis proteins(BMPs) are multi-functional growth factors. They are expressed in retina,retinal pigment epithelium(RPE) and sclera and serve as a regulator in the growth and development of the eye. This article reviewed the chondrogenic potency of the sclera,biochemical and pathological changes of myopic scleral tissue and the differentiation of chondrogenesis by BMP-2. We proposed the hypothesis that BMP-2 can regulate differentiate of scleral fibroblasts and affect the development of myopia.

Finite element modeling of the viscoelastic responses of the eye during microvolumetric changes

A linear viscoelastic finite element model was built to investigate factors that influenced the intraocular pressure (IOP) elevations due to micro-volumetric changes in the eye at three different rates. The viscoelastic properties of the cornea and the sclera, including the instantaneous modulus, equilibrium modulus, and relaxation time constants, parametrically varied to examine their effects on IOP elevations at different rates of volumetric changes. The simulated responses were in good agreement with the previously reported experimental results obtained from porcine globes, showing the general trend of higher IOP elevations at faster rates. The simulations showed that all viscoelastic properties influenced the profile of the dynamic IOP due to volumetric changes, and the relative significance of a specific parameter was highly dependent on the rate of change.

Correlation of discoloration and biomechanical properties in porcine sclera induced by genipin

·AIM: To study the feasibility of using the discoloration to evaluate the biomechanical properties after treating with genipin.·METHODS: Porcine cadaver eyes were treated for30 min with 1.0%(by w/v) genipin. Untreated samples were used as controls. After treatment, scleral strips of4.0 ×10.0-mm2 were cut. The denaturation temperature(Td) measurement and stress-strain test were performed after taking photograph to analyze the color.·RESULTS: Within 24 h after treating with genipin, the sclera exhibited a bluish color which became deeper with time. And the denaturation temperature also was increased gradually. Compared with untreated groups, at1, 6, 12, 24 and 36 h after treatment, the ultimate stress were increased by 56%, 153%, 173%, 225% and 211%respectively. The Young’s modulus at 10% strain also increased by 170%, 246%, 264%, 389% and 288%respectively. There were strong correlation between the discoloration and the biomechanical properties(ΔE-Ultimate stress:R2=0.892, P =0.00; ΔE-Young’s modulus:R2=0.602, P =0.00).·CONCLUSION: Genipin could be used to strengthen collagen gradually in a relatively short time span. And the biomechanical properties could be reliably evaluated via simple visible discoloration.

MULTIPHOTON MICROSCOPY:A NEW APPROACH IN PHYSIOLOGICAL STUDIES AND PATHOLOGICAL DIAGNOSIS FOR OPHTHALMOLOGY

Multiphoton microscopy(MPM),with the advantages of improved penetration depth,decreased photo-damage,and optical sectioning capability,has become an indispensable tool for biomedical imaging.The combination of multiphoton fluorescence(MF)and second-harmonic generation(SHG)microscopy is particularly effective in imaging tissue structures of the ocular surface.This work is intended to be a review of advances that MPM has made in ophthalmic imaging.The MPM not only can be used for the label-free imaging of ocular structures,it can also be applied for investigating the morphological alterations in corneal pathologies,such as keratoconus,infected keratitis,and corneal scar.Furthermore,the corneal wound healing process after refractive surgical procedures such as conductive keratoplasty(CK)can also be studied with MPM.Finally,qualitative and quantitative SHG microscopy is effective for characterizing corneal thermal denaturation.With additional development,multiphoton imaging has the potential to be developed into an effective imaging technique for in vivo studies and clinical diagnosis in ophthalmology.

Scleral TGF-β1 and Smad3 expression is altered by TCM Bu Jing Yi Shi Tablets in guinea pigs with form-deprivation myopia

Objective:To explore whether the traditional Chinese medicine(TCM)Bu Jing Yi Shi Tablets alters the expression of scleral TGF-b1 and Smad3 in guinea pigs with formdeprivation myopia(FDM).Methods:Sixty-five guinea pigs were randomly divided into control,model,low-,medium-,and high-dose treatment groups.Except for the control group,FDM was induced by covering the right eye of each animal with opaque latex.The treatment groups were gavaged with different suspension concentrations of Bu Jing Yi Shi Tablets.Refraction and axial length were performed before and after myopia induction.At the end of the experiment,all right eyes were extracted,and scleral sections were prepared for staining and TGF-b1 and Smad3 immunohistochemistry.Scleral thickness and area,the scleral fibroblast quantity,and scleral TGFb1 and Smad3 expressions were measured.Results:The 5 FDM groups had the same initial axial length and diopter,the final diopter and axial length of the model group were significantly increased compared with the control group and treatment groups(P<.01).The axial length of each treatment group decreased as the dose decreased compared with the model group(P<.01);the total scleral area(P<.05 e.01)and the number of scleral fibroblasts(P<.01)in the model group were significantly lower than the treatment groups.Both the TGF-b1 and Smad3 integral optical densities in the model group were significantly lower than the control and medium-and high-dose treatment groups(P<.01).TGF-b1 and Smad3 mRNAs in the model group were decreased compared with the control group,but increased in expression after treatment.

Biomechanics of sclera crosslinked using genipin in rabbit

AIM：To strengthen the biomechanics of collagen by crosslinking rabbit scleral collagen with genipin to develop a new therapy for preventing myopic progression. METHODS：Ten New Zealand rabbits were treated with 0.5 mmol/L genipin injected into the sub-Tenon＇s capsule in the right eyes. Untreated contralateral eyes served as the control. The treated area was cut into scleral strips measuring 4.0 mm×10.0 mm for stress-strain measurements（n=5）. The remaining five treated eyes were prepared for histological examination.RESULTS：Compared to the untreated scleral strips,the genipin-crosslinked scleral strips showed that the ultimate stress and Young＇s modulus at 10% strain were increased by the amplitude of 130% and 303% respectively,ultimate strain was decreased by 24%. There had no α-smooth muscle actin（α-SMA）positive cells in control and treated sclera. Histologically,there was no sign of apoptosis in the sclera,choroid,and retina; and no side effects were found in the peripheral cornea and optic nerve adjacent to the treatment area.CONCLUSION：Genipin induced crosslinking of collagen can increase its biomechanical behavior by direct strengthening of the extracellular matrix in rabbit sclera,with no α-SMA expression seen in the myofibroblasts. As there is no evidence of cytotoxicity in the scleral,choroidal,and retinal cells,genipin is likely a promising agent to strengthen the weakened sclera to prevent myopic progression.

Biomechanics of the sclera and effects on intraocular pressure

Accumulating evidence indicates that glaucoma is a multifactorial neurodegenerative disease characterized by the loss of retinal ganglion cells （RGC）, resulting in gradual and progressive permanent loss of vision. Reducing intraocular pressure （IOP） remains the only proven method for preventing and delaying the progression of glaucomatous visual impairment. However, the specific role of IOP in optic nerve injury remains controversial, and little is known about the biomechanical mechanism by which elevated IOP leads to the loss of RGC. Published studies suggest that the biomechanical properties of the sclera and scleral lamina cribrosa determine the biomechanical changes of optic nerve head, and play an important role in the pathologic process of loss of RGC and optic nerve damage. This review focuses on the current understanding of biomechanics of sclera in glaucoma and provides an overview of the possible interactions between the sclera and IOP. Treatments and interventions aimed at the sclera are also discussed.

Auricular cartilage versus donor sclera as a wrapping of hydroxyapatite orbital implants

AIM: To retrospectively compare postoperative outcomes after primary enucleation and placement of a hydroxyapatite(HA) implant without wrapping, wrapped with auricular cartilage or donor sclera. METHODS: Medical records of patients presented as intraocular tumor or severe ocular injury were identified from the electronic medical record system. Cases underwent enucleation and HA orbital implantation were enrolled in this study and were divided into 3 groups according to the wrapping material of HA implant. Cases with autogenous cartilage caps were enrolled in group A(n=11), with donor sclera caps in group B(n=12), and without any wrapping material in group C(n=9). Follow-ups were set at 1, 2 wk, 1, 3, 6, and 12 mo after surgery.RESULTS: Altogether 32 cases finished the followup and were enrolled in this study. Three cases(27.27%) in group A, 4 cases(33.33%) in group B, and 4 cases(44.44%) in group C developed one complication each after surgery. In group A, no HA exposure occurred, but conjunctival inclusion cyst occurred in one and severe conjunctive chemosis in two cases. In group B, one HA exposure occurred, conjunctive inclusion cysts occurred in one, severe conjunctive chemosis occurred in one, and conjunctival granuloma occurred in one case. In group C, one HA exposure occurred, severe conjunctive chemosis occurred in two cases, and conjunctival granuloma occurred in one case. The case of exposure of none-wrapped implant was noted in the first 6 mo after placement of the orbital implant. The case of exposure of donor sclerawrapped implant was noted at the 12 mo after placement of the orbital implant. Both exposure cases were treated successfully with conservative treatment.CONCLUSION: With low incidence of implant exposure and mild complications, auricular cartilage can be a good choice of alternative wrapping material of orbit implant with satisfied outcome.

Influence of High Level TGF-β1 on Scleral Thickness

In order to explore the role of TGF-β1 in scleral remodeling and the possible mechanism, the influence of high level TGF-β1 on scleral thickness and the expression of MMP-2 and TIMP-2 was investigated in a TGF-β1 transgenic mouse model. Alb/TGF-β1 （Cys^223225Ser） TGF-β1 transgenic mice were used as experimental subjects and non-transgenic littermates as controls. Plasma levels of TGF-β1 were determined by ELISA. TGF-β1, MMP-2 and TIMP-2 levels in sclera were detected by using Western blot. The thickness of posterior sclera was measured by computerized image analysis of a midsagittal section. Mean difference was analyzed with independent t-test. The results showed plasma levels of TGF-β1 in transgenic mice were 1.68 times as much as that in the controls （P〈0.01）. TGF-β1 levels in the sclera of transgenic mice were 2.68 times of the controls （P〈0.01 ）. Posterior scleral thickness in transgenic mice were significantly thicker than in the controls. There was no significant difference in the MMP-2 levels between transgenic mice and controls, but the TIMP-2 levels were increased significantly in transsgenic mice as compared with those in the controls. It was suggested that high levels of TGF-β1 in transgenic mice could result in the increased scleral thickness by inducing the expression of TIMP-2 to suppress the activity of MMP-2, finally inhibiting the degradation of collagen.

AB008:Structural and molecular changes in cornea and sclera of highly myopic-astigmatic chicks

Myopia and astigmatism, two common refractive errors frequently co-exist, are degrading vision at all working distances in populations worldwide. Eyeballs having high degrees of myopia and astigmatism are known to exhibit abnormal eye shape at the anterior and posterior eye segments, but whether the outer coats of these abnormal eyeballs, cornea anteriorly and sclera posteriorly, are regulated by region-specific molecular mechanism remains unclear. Here we presented the changes in eye shape and mRNA expression levels of three genes (MMP2, TIMP2, and TGFB2), all known to participate in extracellular matrix organization, at five regions of the cornea and sclera in chickens developing high myopia and astigmatism induced by form deprivation. Our results showed that, compared to normal chicks, the highly myopic-astigmatic chicks had significantly astigmatic cornea, deeper anterior chamber, longer axial length, and higher expressions of all three genes in the superior sclera. These results imply that local molecular mechanism may manipulate the eye’s structural remodeling across the globe during refractive eye growth.

Modeling and Simulation of Human Cornea for the Measurement of Intraocular Pressure (IOP) through Eyelid

This article describes a study based on the use of an instrumented form of applanation and indentation tonometry through eyelid.The methods and devices which are available for the measurement of intraocular pressure(IOP)have their own limitations.These cause discomfort to the patients during IOP measurement.Also these methods,used to measure IOP over cornea,need anesthesia.In the present work,an attempt is made to develop a device for the measurement of IOP through eyelid which eliminates the need of anesthesia and enhance the patient’s comfort and convenience of the clinician.To represent the results of proposed technique,the human eye modeled with cornea,sclera and also with the eyelid,is used.Furthermore,simulation results of stress values for the range of IOP i.e.5-40 mm of Hg are presented and discussed comparatively with eyelid and without eyelid i.e.directly‘on cornea’methods.

Characterization of the geometric properties of the sclero-conjunctival structure: a review

To revise the peer-reviewed literature on geometric properties of the scleral-conjunctival structure in order to define their clinical relevance and the potential relationship between their changes and myopia development or progression.A bibliographic search focused on the study of the geometry of conjunctiva and/or sclera as well as those studies evaluating the relationship between geometric changes in the scleral-conjunctival structure and myopia was carried out.Several studies have been performed with different diagnostic technologies,including optical coherence tomography,profilometry and Scheimpflug imaging,to detect geometric changes of the scleralconjunctival tissue in different physiological conditions of the eye,after use of contact lenses and in different ocular pathologies.Likewise,these technologies have been shown to be a valuable clinical tool to optimize scleral contact lens fitting.Future studies should investigate new potential clinical applications of such technologies,including the evaluation of anterior scleral changes related to myopia,as well as to define standardized clinical standard operating procedures for obtaining accurate and reproducible clinical measurement of the scleral-conjunctival morphology.