Effect of topical 0.05% cyclosporine A on corneal endothelium in patients with dry eye disease

· AIM: To determine the effect of topical 0.05% cyclosporine A (CsA) on corneal endothelium in patients with dry eye disease. · METHODS: Observational, prospective, case series study. Fifty-five eyes of 29 consecutive patients (9 males and 20 females; median age: 66.8 years, interquartile range: 61 -73.2 years) with moderate -severe dry eye disease were evaluated. All patients were treated with topical 0.05% CsA ophthalmic emulsion twice a day in addition to lubricant eyedrops 5 times a day. The follow- up period was 12 months. Before treatment and at 3 and 12 months post -treatment central corneal specular microscopy was performed. The endothelial cell density (ECD), coefficient of variation of cell size (CoV), and percentage of hexagonal cells (Hex %) were analyzed. ·RESULTS: The median ECDs pre-treatment and at 3 and 12 months post-treatment were 2 352.5/mm 2 (inter- quartile range, 2 178 -2548.5), 2 364/mm 2 (interquartile range, 2 174.25 -2 657.5), and 2 366 cells/mm 2 (inter - quartile range, 2 174.75-2 539.75), respectively (P=0.927, one way ANOVA). The median CoVs pre-treatment and at 3 and 12 months post -treatment were 34.5 (interquartile range, 30 -37), 35 (interquartile range, 30 -38), and 34 (interquartile range, 30.75-38.25), respectively (P=0.7193, one way ANOVA). The median Hex % values pre - treatment and at 3 and 12 months post -treatment were 53 (interquartile range, 47 -58), 54 (interquartile range, 45.75 -59), and 50.5 (interquartile range, 45.75 -58), respectively (P=0.824, one way ANOVA). · CONCLUSION: Treatment of patients with dry eye disease for 12 months with topical 0.05% CsA does not seem to cause substantial changes on corneal endothelium.

Differences in energy and corneal endothelium between femtosecond laser-assisted and conventional cataract surgeries：prospective,intraindividual,randomized controlled trial

AIM： To compare intraoperative phacoemulsification parameters and its effect on the corneal endothelium of eyes undergoing femtosecond laser-assisted cataract surgery（FLACS） versus conventional phacoemulsification（CP） cataract surgery.METHODS： Two hundred eyes from one hundred patients were included in a prospective, non-blinded, randomized, controlled, intraindividual clinical study. One hundred eyes underwent FLACS while their one hundred fellow eyes underwent CP. All surgeries were performed using the Victus？ femtosecond laser platform and Infinity？ Vision System phacoemulsification machine. Primary outcome measure was endothelial cell density 6 mo after surgery. Secondary outcome measures included central corneal thickness（CCT）, average cell area, standard deviation, coefficient of variation and hexagonality before surgery and 6 mo after surgery and endothelial cell density loss during this period were also evaluated. Intraoperative efficiency parameters [cumulative dissipated energy（CDE）, total intraocular surgery time, total ultrasound time, total phacoemulsification time, total torsional energy time, total aspiration time, ultrasound energy, torsional amplitude and fluid required during surgery] were also collated. RESULTS： Data from these patients was not considered for analysis. Data from 92 patients were analysed. Postoperative endothelial cell density（cells/mm2） between groups（2211.88±392.49 CP; 2246.31±403.48 FLACS） was not statistically significant（P=0.869）. Total ultrasound time, torsional energy time, CDE and fluid requirements were significantly lower the FLACS group（P〈0.05）. Other parameters did not show statistically significant difference between FLACS and CP.CONCLUSION： FLACS displays significant improvements in phacoemulsification parameters in comparison to CP. There are no significant differences in corneal endothelium measures between FLACS and CP.

STUDY IN CYTOTOXICITY OF GENTAMYCIN TO CORNEAL EPITHELIUM AND ENDOTHELIUM IN TISSUE CULTURE

A study in cytotoxicity of gentamyein to tissue-cultured bovine corneal endothelial cells and rabbit corneal epithelial cells is reported. When the cultured cells reached confluence, they were exposed to tissue culture media containing gentamycin for 6 hours. We founl that 0.5% gentamycin caused significant damage to corneal epithelial cells---diffuse plasmolysis, with scattered cell necrosis and 5% loss.While corneal endothelial cells were exposed to 1.6 mg/ml gentamycin, extensive cell loss (approximate- ly 15%) was observed. The damaged cells recovered their normal morphology after 24 hours. When the concentration of gentamycin increased twice, serious damage to cells occured. The area of cell loss reached 40%, and the recovery of cellular morphology Was much slower. This study demonstrates that gentamycin potential cytotoxicity to corneal epithelium and endothelium, suggesting that gentamycin should be rationally used in the treatment of ocular diseases.

EXPERIMENTAL STUDY ON THE CORNEAL ENDOTHELIUM OF TRAUMATIC CATARACT

The cell morphology of corneal endothelium in 84 mice with experimental traumatic cataract was investigated with stained corneal buttons. In the experimental group, the boundaries between adjacent corneal endothelial cells were significantly distorted, some cell boundaries manifested degenerative changes that led to coalescence of the cells. The mean density and mean area of endothelial cells of the controls showed significant difference from those of the experimental group during the 12 weeks of observ...

Short term effects of small incision lenticule extraction surgery on corneal endothelium

AIM： To assess the effects of small incision lenticule extraction（SMILE） surgery on the corneal endothelium at1 d to 1mo postoperatively.·METHODS： A retrospective, observational study was conducted on 47 patients（47 eyes） who received SMILE surgery. Patients were grouped according to contact lens wear condition. The corneal endothelium was examined preoperatively and at 1d, 1wk and 1mo postoperatively.The corneal endothelium was analyzed for endothelial cell density（ECD）, percentage of hexagonal cells, and coefficient of variation（CV） of cell size.·RESULTS： There were no significant decrease in the ECD, percentage of hexagonal cells or increase in CV at1 d, 1wk and 1mo postoperatively（P 〉0.05）. However,there was a small increase of ECD by 2.88% in contact lens wearers（78.26±113.62 cell/mm2, P 〈0.05）.· CONCLUSION： SMILE has no significant adverse effects on the corneal ECD and morphology during 1mo follow-up time.

Hammered silver appearance of the corneal endothelium in Fuchs uveitis syndrome:A case report

BACKGROUND Hammered silver appearance of the corneal endothelium is considered a characteristic change in iridocorneal-endothelial syndrome.Herein we report an interesting case of hammered silver appearance of the corneal endothelium in Fuchs uveitis syndrome(FUS).CASE SUMMARY A 49-year-old man with progressive vision loss in the right eye for one year was admitted to our hospital.The clinical manifestations of the patient’s right eye were mild conjunctival hyperemia,scattered stellate keratic precipitates on the corneal endothelium,normal depth anterior chamber,2+cellular reaction in the aqueous humor,diffuse iris depigmentation,absence of synechia,Koeppe nodules,opalescent lens,and vitreous opacity.FUS and a complicated cataract were diagnosed based on the typical clinical manifestations.The corneal endothelial changes were recorded in detail by slit-lamp examination,specular microscopy,and in vivo confocal microscopy before cataract extraction,revealing a hammered silver appearance of the corneal endothelium in the affected eye,a wide-band dark area,as well as irregular corneal endothelial protuberances and dark bodies of various sizes.Subsequently,the patient underwent phacoemulsification combined with intraocular lens implantation,and his postoperative visual acuity recovered to 1.0.CONCLUSION Hammered silver appearance of the corneal endothelium in FUS,which is considered a more serious manifestation of endothelial damage,is rare and may be caused by many irregular protrusions in the corneal endothelium.

Evaluation of corneal endothelium after UVA/riboflavin cross-linking in thin keratoconic corneas

Dear Sir,UVA/riboflavin cross-linking （CXL） has been used clinically applied for the treatment of keratoconus and corneal edema via enhancement of corneal stiffness The safety of the corneal endothelium is of prime importance during CXL treatment. In clinical practice, a corneal thickness （CT） of 400um has traditionally been regarded as the minimum treatable thickness, thereby avoiding damage to the corneal endothelium Although CXL has been applied to thinner corneas, using a hypoosmotic solution onto cornea and inducing edema . CXL safety still needs further evaluation because of lower relative concentration of collagen in the hydrated stroma . This study aims to evaluate the changes of corneal endothelial density （ECD） in cases where the CT is 〈400 um before iatrogenic corneal swelling and CXL treatment.

AB086.Influence of the intraocular pressure on the expression of tight junctions in the corneal endothelium

Background:Cells are influenced by their environment.In vivo,the corneal endothelium is subjected to intraocular pressure(IOP).The purpose of this project was to evaluate in vitro,the effect of the IOP on the formation of tight junctions in the corneal endothelium.Methods:Cultivated corneal endothelial cells(P2-P3;n=6 populations)were seeded on devitalized on corneas(n=10 pairs).Native corneas and devitalized corneas were respectively used as positive(n=2 pairs)and negative controls(n=3 pairs).Corneas were placed in artificial anterior chambers and subjected to a hydrostatic pressure between 0.3 and 0.4 psi during 4-5 days.Unpressured control corneas were maintained in cell culture dishes.Pictures of the corneas were taken following the experiment to assess stromal transparency.Morphology,corneal thickness and distribution of ZO-1,n-cadherin,b-catenin,NaK ATPase pump and HCO3-cotransporter were evaluated by electron microscopy,histological staining and immunofluorescences.Results:Pressure treated corneas were more transparent than the controls.Thickness was accordingly reduced by 38.4%±4.9%for cultivated endothelium and 32.2%±2.7%for native endothelium.Negative controls change in transparency and thickness were marginal.Pressure treated cells showed none or at most marginal difference in morphology and expression of ZO-1,n-cadherin,b-catenin,NaK ATPase pump and HCO3-cotransporters and failed to recreate a phenotype similar to native corneas.Pressure however increased cortical localisation of the protein ZO-1 in both cultivated and native endothelium.Conclusions:These results suggest that anterior chamber hydrostatic pressure may enhance endothelial functionality by modulating the distribution of tight junction’s proteins.

Stromal lenticule addition keratoplasty with corneal crosslinking for corneal ectasia secondary to FS-LASIK:a case series

●AIM:To explore the clinical efficacy and safety of stromal lenticule addition keratoplasty(SLAK)with corneal crosslinking(CXL)on patients with corneal ectasia secondary to femtosecond laser-assisted in situ keratomileusis(FS-LASIK).●METHODS:A series of 5 patients undertaking SLAK with CXL for the treatment of corneal ectasia secondary to FS-LASIK were followed for 4-9mo.The lenticules were collected from patients undertaking small incision lenticule extraction(SMILE)for the correction of myopia.Adding a stromal lenticule was aimed at improving the corneal thickness for the safe application of crosslinking and compensating for the thin cornea to improve its mechanical strength.●RESULTS:All surgeries were conducted successfully with no significant complications.Their best corrected visual acuity(BCVA)ranged from 0.05 to 0.8-2 before surgery.The pre-operational total corneal thickness ranged from 345-404μm and maximum keratometry(Kmax)ranged from 50.8 to 86.3.After the combination surgery,both the corneal keratometry(range 55.9 to 92.8)and total corneal thickness(range 413-482μm)significantly increased.Four out of 5 patients had improvement of corneal biomechanical parameters(reflected by stiffness parameter A1 in Corvis ST).However,3 patients showed decreased BCVA after surgery due to the development of irregular astigmatism and transient haze.Despite the onset of corneal edema right after SLAK,the corneal topography and thickness generally stabilized after 3mo.●CONCLUSION:SLAK with CXL is a potentially beneficial and safe therapy for advanced corneal ectasia.Future work needs to address the poor predictability of corneal refractometry and compare the outcomes of different surgical modes.

Clinical associations of corneal neuromas with ocular surface diseases

Corneal neuromas,also termed microneuromas,refer to microscopic,irregula rly-shaped enlargements of terminal subbasal nerve endings at sites of nerve damage or injury.The formation of corneal neuromas results from damage to corneal nerves,such as following corneal pathology or corneal or intraocular surge ries.Initially,denervated areas of sensory nerve fibers become invaded by sprouts of intact sensory nerve fibers,and later injured axons regenerate and new sprouts called neuromas develop.In recent years,analysis of corneal nerve abnormalities including corneal neuromas which can be identified using in vivo confocal microscopy,a non-invasive imaging technique with microscopic resolution,has been used to evaluate corneal neuropathy and ocular surface dysfunction.Corneal neuromas have been shown to be associated with clinical symptoms of discomfort and dryness of eyes,and are a promising surrogate biomarker for ocular surface diseases,such as neuropathic corneal pain,dry eye disease,diabetic corneal neuropathy,neurotrophic keratopathy,Sjogren's syndrome,bullous keratopathy,post-refra ctive surgery,and others.In this review,we have summarized the current literature on the association between these ocular surface diseases and the presentation of corneal microneuromas,as well as elaborated on their pathogenesis,visualization via in vivo confocal microscopy,and utility in monitoring treatment efficacy.As current quantitative analysis on neuromas mainly relies on manual annotation and quantification,which is user-dependent and labor-intensive,future direction includes the development of artificial intelligence software to identify and quantify these potential imaging biomarkers in a more automated and sensitive manner,allowing it to be applied in clinical settings more efficiently.Combining imaging and molecular biomarkers may also help elucidate the associations between corneal neuromas and ocular surface diseases.

Transplanting embryonic stem cells onto damaged human corneal endothelium

AIM To investigate whether human embryonic stem cells(hESCs) could be made to attach, grow and differentiate on a human Descemet's membrane(DM).METHODS Spontaneously differentiated hESCs were transferred onto a human corneal button with the endothelial layer removed using ocular sticks. The cells were cultured on a DM for up to 15 d. The genetically engineered hESC line expressed green fluorescent protein, which facilitated identification during the culture experiments, tissue preparation, and analysis. To detect any differentiation into human corneal endothelial-like cells, we analysed the transplanted cells by immunohistochemistry using specific antibodies.RESULTS We found transplanted cells form a single layer of cells with a hexagonal shape in the periphery of the DM. The majority of the cells were negative for octamer-binding transcription factor 4 but positive for paired box 6 protein, sodium potassium adenosine triphosphatase(NaKATPase), and Zona Occludens protein 1. In four of the 18 trials, the transplanted cells were found to express CK3, which indicates that the stem cells differentiated into corneal epithelial cells in these cases. CONCLUSION It is possible to get cells originating from hESCs to become established on a human DM, where they grow and differentiate into corneal endothelial-like cells in vitro.

The role of corneal endothelium in macular corneal dystrophy development and recurrence

Macular corneal dystrophy(MCD)is a progressive,bilateral stromal dystrophic disease that arises from mutations in carbohydrate sulfotransferase 6(CHST6).Corneal transplantation is the ultimate therapeutic solution for MCD patients.Unfortunately,postoperative recurrence remains a significant challenge.We conducted a retrospective review of a clinical cohort comprising 102 MCD patients with 124 eyes that underwent either penetrating keratoplasty(PKP)or deep anterior lamellar keratoplasty(DALK).Our results revealed that the recurrence rate was nearly three times higher in the DALK group(39.13%,9/23 eyes)compared with the PKP group(10.89%,11/101 eyes),suggesting that surgical replacement of the corneal endothelium for treating MCD is advisable to prevent postoperative recurrence.Our experimental data confirmed the robust m RNA and protein expression of CHST6 in human corneal endothelium and the rodent homolog CHST5 in mouse endothelium.Selective knockdown of wild-type Chst5 in mouse corneal endothelium(AC^(siChst5)),but not in the corneal stroma,induced experimental MCD with similar extracellular matrix synthesis impairments and corneal thinning as observed in MCD patients.Mice carrying Chst5 point mutation also recapitulated clinical phenotypes of MCD,along with corneal endothelial abnormalities.Intracameral injection of wild-type Chst5 rescued the corneal impairments in AC^(siChst5)mice and retarded the disease progression in Chst5 mutant mice.Overall,our study provides new mechanistic insights and therapeutic approaches for MCD treatment by highlighting the role of corneal endothelium in MCD development.

Evaluation of corneal parameter changes under different accommodative stimuli with Scheimpflug imaging-based tomography

AIM:To evaluate the reliability of measurements of corneal changes with accommodation in healthy eyes using a Scheimpflug imaging-based system and how these measurements distribute in the normal population.METHODS:Prospective,non-randomized,comparative study including 27 healthy subjects(54 eyes),including emmetropia(13 eyes),myopia(17 eyes),hyperopia(4 eyes)and astigmatism(20 eyes)groups.In all cases,a complete eye examination was performed,including the analysis of corneal changes with different accommodative stimuli(+2.00,0.00 and-3.00 D)using the Pentacam AXL system.The investigation was structured in 2 phases:repeatability analysis and characterization of accommodation-related corneal changes in healthy populations.RESULTS:In the repeatability analysis,the index of height asymmetry(IHA)showed the greatest variability with the three accommodative stimuli,being the results for the rest of parameters acceptable.The group of emmetropes showed significant differences with accommodative changes in the position of maximum keratometry(Kmax;P<0.05),whereas in the astigmatism group,significant changes were not only observed in the position of Kmax,but also in minimum corneal thickness(MCT),corneal spherical aberration,and total and low order aberration root mean square(all P<0.05).Likewise,a significant difference was found in the displacement of the X position of Kmax with+2.00 D and-3.00 D in the myopia group(P=0.033)as well as in changes with+2.00 D and-3.00 D in the magnitude of the position vector of Kmax in the emmetropia group(P<0.05).No significant changes were found between accommodative stimuli in the displacement of coordinates of MCT(P≥0.109).CONCLUSION:The position of Kmax and MCT in healthy corneas can change significantly when presenting different accommodative stimuli using the accommodation mode of the Pentacam system,with different trends in these accommodation-related corneal changes between refractive errors.Likewise,the consistency of the measurements obtained with Scheimpflug has been confirmed.

Resistant corneal ulcers in a tertiary care ophthalmic center in Egypt: 10 years epidemiological study

AIM:To investigate the magnitude of problem caused by resistant corneal ulcers and its epidemiological characteristics.METHODS:Patients with corneal lesions were selected and carefully examined and cases with resistant corneal ulcers were further investigated and data were recorded using a specific data sheet designed in hospital.Then,collected data from patients were statistically analyzed.RESULTS:Totally 1939 cases were included in the study,including 816 fungal cases(42.1%)and 1123(57.9%)non-fungal cases.Age of the participants ranged from 18 to 73y.Fungal cases were more common in middle age(35-55y).Men were more affected(53.5%)of cases included in the study.Keratomycosis affected more unskilled personnel(75.1%),large families with small houses(higher crowding index 73.9%),rural(64.5%)residence.Patients with sanitary water sources(34.8%)and waste disposal(24.4%)were less affected.CONCLUSION:Keratomycosis is more frequent in unskilled personnel,rural locations,outdoor water sources and insanitary waste disposal systems.Corneal trauma and contact lens are common risk factors.

Corneal and intraocular pressure changes associated to the circadian rhythms:a narrative review

AIM:To synthesize the current body of research regarding the diurnal variations in intraocular pressure(IOP)and corneal biomechanical and morphological parameters,highlighting their significance in various eye conditions.METHODS:A comprehensive review of studies on the diurnal variations of IOP and corneal parameters was conducted.Tonometry findings from various studies were assessed,including the Goldmann applanation tonometry(GAT)and non-contact tonometers.Data on the variations in central corneal thickness(CCT),corneal curvature,and corneal biomechanics measured by the Ocular Response Analyzer system across different population groups was extracted and analyzed.RESULTS:In both healthy subjects and those with Fuchs dystrophy,IOP and CCT demonstrate marked diurnal declines.GAT remains the gold standard for tonometry,with the highest reliability.However,its measurements are influenced by CCT.Keratoconus patients and those with pseudoexfoliation showed significant diurnal variations in IOP.The biomechanical parameters,especially corneal hysteresis(CH)and the corneal resistance factor(CRF),largely remain stable throughout the day for most of eye conditions,with some exceptions.Notably,the corneal morphology diurnal variation,particularly curvature,yielded mixed conclusions across studies.CONCLUSION:Circadian rhythms significantly influence various corneal parameters,most notably IOP and CCT.Further studies should emphasize standardized approaches larger sample sizes,and delve deeper into less-explored areas,such as the effects of orthokeratology lenses on diurnal biomechanical shifts.

AB028.Corneal endothelium decompensation in patients with chronic hypotony after glaucoma surgery

Background:To describe and discuss four cases of corneal endothelial decompensation secondary to chronic hypotony after glaucoma surgery.Methods:A retrospective case review was undertaken for four4 patients over a 20-year period from a single glaucoma surgeon.These data were collected from the clinical records of each subject included in the study:(I)patient demographic characteristics;(II)past ocular history and indication for surgery;(III)ocular vitals;(IV)complications from glaucoma surgery;(V)corneal exam and pathology and the indication for corneal transplant;(VI)surgical interventions during the period of follow-up.Results:Four patients sustained chronic hypotony(range,3-18 years)after glaucoma surgery.In most of these eyes during relative hypotony,long thin vertical folds were often noted in the superficial cornea(possibly involving Bowman’s layer and the epithelium),leading to fluorescein pooling.They subsequently developed marked corneal pathologies including stromal edema,diminished endothelial density,microcyst formation,corneal erosion,Descemet folds,superficial punctate keratitis and bullous keratopathy.Three of them received Descemet stripping automated endothelial keratoplasty(DSAEK)and regained functional vision.Conclusions:This case series demonstrates a unique clinical entity in which corneal endothelial demise developed in the context of chronic hypotony.The mechanism underlying this entity,which we term“chronic hypotony corneal endotheliopathy(CHCE)”,remains unclear.We hypothesize that it can be due to a combination of tectonic instability and energy disturbance of the cornea.In clinical practice,it is important to monitor endothelial cell count in patients with persistent hypotony,especially those who had procedures such as glaucoma surgery that can precipitate endothelial injury.

The Corneal Endothelium in Children after Congenital Cataract Surgery--A Comparison of Pre- and Post-Operative Results

Three months after surgery, the research group showed significantly statistical improvement in visual acuity, a statistically significant decrease in corneal endothelial cell density, a statistically significant increase in the percentage of 5 and 8 sided cells and a statistically significant decrease in the percentage of six sided cells. Central corneal thickness and the percentage of 4 and 7 and more than 8 sided did not change in a statistically significant way. Comparing the test group and control group, no statistically significant differences were detected in the examined parameters. The present study also shows that the cornea in the eyes with congenital cataract does not show statistically significant changes in the density and the morphology of the corneal endothelial cells and the thickness of the cornea and in terms of corneal thickness in comparison to the corneas of healthy eyes. Although in corneas undergoing cataract occurs statistically significant changes, the influence of the cornea does not affect the improvement in visual acuity which was also demonstrated in this study.

Silicone oil as a corneal lubricant to reduce corneal edema and improve visualization during

AIM:To evaluate the efficacy and safety of silicone oil(SO)as a corneal lubricant to improve visualization during vitrectomy.METHODS:Patients who underwent vitreoretinal surgery were divided into two groups.Group 1 was operated on with initial SO(Oxane 5700)as a corneal lubricant.Group 2 was operated on with initial lactated ringer’s solution(LRS)and then replaced with SO as required.Fundus clarity was scored during the surgery.Fluorescein staining was performed to determine the damage to corneal epithelium.RESULTS:Totally 114 eyes of 114 patients were included.Single SO use maintained a clear cornea and provided excellent visualization of surgical image.In group 1,the fundus clarity was grade 3 in 41/45 eyes and grade 2 in 4/45 eyes.In group 2,corneal edema frequently occurred after initial LRS use.The fundus clarity was grade 3 in 19/69 eyes,2 in 37/69 eyes and 1 in 13/69 eyes(P<0.05).SO was applied in 29 eyes of initial LRS use with subsequent corneal edema,which eliminated the corneal edema in 26 eyes.Corneal fluorescein staining score in group 1 was 0 in 28 eyes,1 in 11 eyes and 2 in 6 eyes,and 40,20 and 9,respectively,in group 2(all P>0.05).CONCLUSION:The use of SO as a corneal lubricant is effective and safe for preserving and improving corneal clarity and providing clear surgical field during vitrectomy.

Small-diameter acellular porcine corneal stroma for peripheral corneal ulceration treatment

AIM:To evaluate the clinical efficacy of small-diameter acellular porcine corneal stroma(SAPS)for the treatment of peripheral corneal ulceration(PCU).METHODS:This retrospective clinical study included 18 patients(18 eyes)with PCU between April 2018 and December 2020.All patients had PCU and underwent lamellar keratoplasty with SAPS.Observation indicators included preoperative and postoperative best-corrected visual acuity(BCVA)and transparency of SAPS.The infection control rate in the surgical eye-lesion area was also calculated.RESULTS:Eighteen patients underwent lamellar keratoplasty with SAPS to treat PCU.None of the patients experienced rejection after 6mo(18/18)and 12mo(16/16)of follow-up.The BCVA(0.47±0.30)at the 6mo followup after operation was significantly improved compared with the baseline(0.99±0.80),and the difference was statistically significant(Z=-3.415,P<0.05).The BCVA at the 12mo follow-up after operation was not statistically significant compared to the 6mo(Z=0,P=1).With time,the SAPS graft gradually became transparent.At the 6mo(18/18)and 12mo(16/16)follow-up,none of the patients had recurrent corneal infection.CONCLUSION:SAPS is clinically effective in the treatment of PCU,improving the patient’s BCVA and reducing the incidence of rejection after keratoplasty.

Effect of mitomycin C on the corneal endothelial cells of Saudi patients with myopia after transepithelial photorefractive keratectomy:a two-armed cohort study

AIM:To study the effect of mitomycin C(MMC)applied during transepithelial photorefractive keratectomy(TPRK)on the corneal endothelium one week(W1)and three months(M3)after surgery and its determinants.METHODS:In this two-armed cohort study conducted in 2022,eyes treated with MMC during TPRK(group 1)were compared with eyes not treated with MMC(group 2).The corneal endothelial cell(EC)count,EC density(ECD;cells/mm2),average(μm2),standard deviation(μm2),coefficient of variation(CV%),ECmax,ECmin,and EC percentage of hexagonality were estimated at W1 and M3.The postoperative changes in the EC count in the two groups were compared and correlated with the other independent variables.RESULTS:Group 1 had 26 eyes,and group 2 had 78 eyes.All TPRK indices were significantly higher for the eyes in group 1 than for those in group 2.The MMC usage was not a significant predictor of the change in ECD(P=0.644),change in CV(P=0.374),and change in the percentage of hexagonality of EC(P=0.164)at W1.However,the use of MMC was a significant predictor of changes in CV(P=0.014)and the change in the percentage of hexagonality of EC(P=0.039)at M3.The duration of laser exposure and the size of the optical zone influenced the correlation of MMC use with the changes in EC indices,postoperatively.CONCLUSION:The use of MMC doesn’t affect ECD,CV,and percentage of hexagonality at W1 if other surgical indices are considered.At M3 after operating myopic eyes by TPRK,MMC significantly influence the CV and percentage of hexagonality.The duration of the laser application and the size of the optical zone should be considered when determining the effect of MMC on the EC indices.