Anterior segment optical coherence tomography for identifying muscle status in strabismus surgery

Anterior segment optical coherence tomography （AS-OCT） finds very few indications in the domain of strabismus surgery. Current applications remain restricted to determining limbus-muscle insertion distance and anterior segment changes after strabismus surgery. We discuss two cases of operated strabismus surgery where AS-OCT imaging helped in identifying the operated eye and/or extra ocular muscles （EOM） and thus proved instrumental in planning and management.

Measurement of anterior chamber volume with rotating scheimpflug camera and anterior segment optical coherence tomography

Background Measurement of anterior segment parameters plays an important role in diagnosis and treatment of glaucoma. The objective of this study was to evaluate the repeatability and reproducibility of anterior chamber volume （ACV） measurements with rotating scheimpflug camera （RSC） and to examine agreement with anterior segment optical coherence tomography （AS-OCT）. Methods Thirty nine healthy normal subjects were recruited from the Eye Center of Tongren Hospital. ACV was measured using RSC and AS-OCT in a randomly selected eye for each subject. For RSC measurements, both automatic and manual ACV measurements and 2 independent operators＇ ACV measurements were obtained. All subjects were invited for 3 visits within a week to evaluate repeatability and reproducibility of ACV measurement by RSC. Agreement was evaluated between RSC and AS-OCT. Results Good repeatability and reproducibility were found for both automatic and manual ACV measurements obtained by RSC. For intrasession repeatability, coefficient of variation （CVw） and intraclass correlation coefficient （ICC） values for automatic were 3.52% and 0.98; the values for manual were 3.44% and 0.97, respectively. For intersession reproducibility, the respective CVw and ICC values were 3.96% and 0.96. Good agreement was also found in 2 operators for both automatic and manual ACV measurements; nevertheless, poor agreement was found between RSC and AS-OCT （95% confidence interval （CO for agreement of automatic RSC measurement versus AS-OCT were -96.3 to 72.8 pl and 95% CI for agreement of manual RSC measurement versus AS-OCT were between 41.7 to 10.1 #1 ）. Conclusions Both RSC automatic and manual ACV measurements showed good repeatability and reproducibility, and showed comparable agreement between 2 independent operators, but poor agreement was found between RSC and AS-OCT.

Evaluation of dry eye disease in newly diagnosed anxiety and depression patients using anterior segment optical coherence tomography

Background:We aimed to evaluate dry eye diseases(DED)in patients with newly diagnosed depression and anxiety patients.Methods:Forty newly diagnosed depression,35 anxiety patients,and 37 controls without any history of taking psychiatric drugs(or before the beginning of psychiatric medication)and topical ophthalmic drop use,were included in the study.All depression and anxiety diagnoses were performed by an experienced psychiatrist.Beck depression and anxiety tests were used to measure disease severity.Tear film break up time(TBUT),Schirmer’s test,Oxford scores and ocular surface disease index(OSDI)were admiinistered to participants.Anterior segment optical coherence tomography was used to measure tear meniscus heights(TMH),tear meniscus depths(TMD)and tear meniscus areas(TMA).Results:In anxiety and depression groups,Schirmer’s test(mm)(7.24±6.02,6.58±4.9 and 18.79±4.9 respectively,p<0.05)and TBUT(s)(5.62±3.1,5.6±3.5 and 13.37±1.7 respectively,p<0.05)were significantly lower than control group.In addition,OSDI and Oxford scores were significantly higher than controls.OSDI scores were 28.01±19,30.43±18.49,14.38±8.14 respectively(p=0.002)and Oxford scores were 1.9±0.7,2.1±0.6 and 0.7±0.4 respectively(p=0.001).TMD,TMH and TMA values were significantly lower in anxiety and depression groups compared with control groups.Correlations between disease inventory scores and dry eye tests were detected.Conclusions:This study showed a relation between DED and newly diagnosed anxiety and depression patients with no history of psychiatric drug use.The presence of correlation between dry eye tests and disease inventory scores strengthens this association.This is an important knowledge that need to be evaluated in these patients before starting psychiatric medication.

The use of high resolution anterior segment optical coherence tomography for the characterization of conjunctival lymphoma, conjunctival amyloidosis and benign reactive lymphoid hyperplasia

Background:Conjunctival lymphoma,conjunctival amyloidosis and benign reactive lymphoid hyperplasia(BRLH)are conditions that often have a similar appearance on the ocular surface.The use of high resolution anterior segment optical coherence tomography(HR-OCT)enables clinicians to evaluate distinctive differences in tissue morphology and cellular patterns in various ocular surface conditions.In this study,we characterize the morphological differences seen in conjunctival lymphoma,conjunctival amyloidosis and BRLH on HR-OCT imaging.Methods:A retrospective chart review was performed of patients with biopsy proven conjunctival lymphoma,conjunctival amyloidosis and BRLH between 2012 and 2019 at the Bascom Palmer Eye Institute.Patients were excluded if HR-OCT imaging was not performed on initial presentation.Results:Thirty-four total eyes of 27 patients were identified.Twenty eyes had conjunctival lymphoma(16 patients),8 eyes had conjunctival amyloidosis(6 patients)and 6 eyes had BRLH(5 patients).All conditions appeared clinically as pink,red or yellow subepithelial lesions but had different features on HR-OCT.In lymphoma,HR-OCT images typically showed homogenous,dark subepithelial lesions with smooth borders,containing monomorphic dot-like infiltrates.HR-OCT images of amyloidosis typically showed heterogeneous,dark lesions with irregular borders,often containing hyperreflective linear infiltrates.HR-OCT images of BRLH showed variable infiltration of the subepithelial tissue,at times with homogenous lesions containing dot-like infiltrates like lymphoma and other times with more hyperreflective,subepithelial tissue.Flow cytometry and gene rearrangement was needed for final differentiation between BRLH and lymphoma lesions.Conclusions:Distinctive features on HR-OCT of conjunctival lymphoma,conjunctival amyloidosis and BRLH can help characterize these lesions beyond what is apparent with the clinical examination.Future studies can further validate this technology’s use with more subtle and challenging lesions.

Anterior and posterior segment structural features of acute primary angle-closure eyes:date based on AS-OCT and SS-OCT

Background:To measure the anterior and posterior segment structural features of acute primary angle-closure(APAC)eyes.Methods:A total of 36 subjects with unilateral APAC were recruited in this study.The ocular biometric characteristics were measured by anterior segment optical coherence tomography(AS-OCT)and swept source optical coherence tomography(SS-OCT),respectively at baseline,2 weeks,and 1 month after surgical intervention.Results:At baseline,when compared with the fellow eyes,APAC-affected eyes showed significantly greater corneal thickness(P=0.004),shallower anterior chamber depth(ACD)(P<0.001),smaller anterior chamber area(ACA)(P=0.013),angle opening distance at 750μm from the scleral spur(AOD750)(P=0.002),trabecular-iris space area at 750μm from the scleral spur(TISA750)(P=0.033),angle recess area(ARA)(P=0.014),and iris area(IARE)(P=0.003),less iris curvature(ICURVE)(P=0.003),and larger lens vault(LV)(P=0.030).After intervention,the corneal thickness was significantly decreased at 1 month(P<0.001),while ACD,ACA,and AOD750 were significantly increased at 2 weeks and 1 month(all P<0.017).Changes in ACD were correlated with decreasing LV(P<0.05).The posterior segment parameters did not change over the 4-week period.Conclusions:When compared with the fellow eyes,APAC-affected eyes had greater corneal thickness,shallower anterior chamber,narrower angle,less ICURVE,and larger LV.After intervention,the corneal thickness was decreased,while the shallower anterior chamber was relieved to some extent.

Assessment of anterior chamber angle changes after phacoemulsification with swept-source OCT

AIM:To assess the changes of anterior chamber angle in patients with shallow anterior chamber after phacoemulsification combined with intraocular lens(IOL)implantation,based on anterior segment swept-source optical coherence tomography(AS-SS-OCT)measurements.METHODS:This was a prospective case control study;sixty eyes of sixty case were scheduled for cataract surgery with normal intraocular pressure(IOP).Based on anterior chamber depth(ACD)and gonioscopy findings,the eyes were divided into two groups:group of shallow anterior chamber and narrow angle(SAC group,30 eyes);and group of normal anterior chamber group with wide angle(NAC group,30 eyes).Measurements of ACD,anterior chamber volume(ACV),iris volume(IV),lens vault(LV),angle opening distance(AOD),angle recess area(ARA),trabecular iris space area(TISA),and trabecular iris angle(TIA)were conducted in each group before and 3mo after surgery.RESULTS:There was no significant difference in age,axial length(AL),corneal curvature,corneal diameter,intraocular pressure,and IV between two groups before surgery,except for the LV(P=0.000).ACD and ACV were prominently larger in the NAC group than the SAC group 3mo after operation(3.69±0.38 vs 3.85±0.39 mm,P=0.025;161.37±19.47 vs 178.26±20.30 mm3,P=0.002).AOD750,ARA750 in nasal and inferior quadrants,TISA750 in all quadrants except temporal,and TIA750 in all quadrants in SAC group were significantly smaller than those in NAC group after operation(all P<0.05).CONCLUSION:Cataract surgery can deepen anterior chamber and increase the width of anterior chamber angle in Chinese subjects,but the angle related parameters including AOD750,ARA750,TISA750,TIA,TISA750,and ACV in patients with shallow anterior chamber and narrow angle do not reach the normal level.

Optical coherence tomography for ocular surface and corneal diseases: a review

The advent of optical coherence tomography(OCT)imaging has changed the way ophthalmologists image the ocular surface and anterior segment of the eye.Its ability to obtain dynamic,high and ultra-high resolution,cross-sectional images of the ocular surface and anterior segment in a noninvasive and rapid manner allows for ease of use.In this review,we focus on the use of anterior segment OCT,which provides an“optical biopsy”or in vivo imaging of various ocular surface and corneal pathologies,allowing the clinician to diagnose diseases otherwise not visualized by traditional methods.The utility of anterior segment OCT for various anterior segment pathologies is reviewed.

Agreement of corneal curvature and central corneal thickness obtained from a swept-source OCT and Pentacam in ectopia lentis patients

AIM:To assess the inter-device consistency of corneal curvature and central corneal thickness between Pentacam and a swept-source Fourier-domain anterior segment optical coherence tomography(AS-OCT)in ectopia lentis patients.METHODS:Totally 72 eyes of ectopia lentis patients were recruited.Central corneal thickness(CCT),corneal curvature values and corneal astigmatism were obtained from both the Pentacam and AS-OCT(CASIA2).Repeatability was evaluated for both devices.The coef ficient of repeatability(COR)and the relative COR was calculated.Bland-Altman plots were conducted to evaluate the interdevice agreement of measurement.Orthogonal linear regression was used to examine any proportional bias.RESULTS:The mean difference of CCT,steep anterior corneal cur vature(anterior K_S),flat anterior corneal curvature(anterior K_f),anterior corneal astigmatism(ACA),steep posterior corneal cur vature(posterior K_S),flat posterior corneal cur vature(posterior K_f),posterior corneal astigmatism(PCA),steep true net power(TNP K_S),flat true net power(TNP K_f)and total corneal astigmatism(TCA)between Pentacam and CASIA2 were 7.03±9.70μm,-0.19±0.41 D,-0.27±0.35 D,0.04±0.47 D,-0.17±0.23 D,-0.11±0.11 D,-0.02±1.02 D-0.41±0.43 D,-0.52±0.46 D,and-0.15±0.96 D,respectively.For measurement of TNP K_f with the Pentacam and CASIA2,a mean difference of 0.52 D and COR of 0.90 with P=0.02 was detected.There was no significant difference in CCT(P=0.393),anterior K_f(P=0.107),anteriorKs(P=0.414),ACA(P=0.131),posterior K_f(P=0.286),posterior Ks(P=0.418),PCA(P=0.105),TNP Ks(P=0.054),and TCA(P=0.977)between Pentacam and CASIA2.CONCLUSION:Our study reveals good agreement of CCT,corneal curvature and corneal astigmatism measured by CASIA2 and Pentacam in ectopia lentis patients.However,there was significant difference for CCT and corneal curvature values obtained by the two devices.

Descemet＇s membrane detachments post cataract surgery：a management paradigm

Descemet’s membrane detachments （DMD） are relatively common after cataract surgery and most do not require any treatment. However, if large DMD are not treated appropriately, significant visual morbidity can ensue. We aim to develop a guideline for the management of DMD post cataract surgery based on a retrospective review of all cases encountered at the Royal Victorian Eye and Ear Hospital, Melbourne, Australia over a 4-year period from 2010 to 2014. We suggest conservative management if the visual axis is not involved; however, after 3mo surgical intervention may be warranted to prevent corneal sequelae. In cases where the visual axis is involved we suggest early intervention with air tamponade. The main risk factor for irreversible corneal oedema and subsequent endothelial transplant appears to be direct endothelial trauma rather than the DMD itself.

Correlation between corneal demarcation line depth in epithelium-off and trans-epithelium accelerated corneal cross linking and keratoconus progression

AIM:To compare corneal demarcation line(DL)depth in both accelerated epithelium-off and trans-epithelium cross linking(CXL)using anterior segment optical coherence tomography(AS-OCT)and its relation to maximum keratometry(Kmax)progression in both techniques.METHODS:A prospective comparative interventional study where patients with mild to moderate keratoconus(KC)were classified into two groups:accelerated epitheliumoff and trans-epithelium CXL based on corneal pachymetry.Assessment of corneal DL depth was carried out after 3mo by AS-OCT.Kmax readings were evaluated after one year follow up using the Scheimpflug imaging system.RESULTS:Study included 74 eyes of 44 patients.Group A underwent epithelium-off CXL(41 eyes),while Group B underwent trans-epithelium CXL(33 eyes).At 3mo follow up,mean corneal DL depth in Group A was 219.9±58.4μm while in Group B was 127.2±7.8μm(P<0.05).The mean Kmaxchangedfrom51.9±3.9to51.3±4.2dioptersin Group A and from 53.1±4.1 to 53.6±5 diopters in Group B with insignificant difference in Kmax changes in either group(P>0.05).In addition,no significant change in corneal pachymetry was found in both groups(meanchange at 1y:6.4±4.7 and-10.1±2.3μm in Groups A and B respectively).CONCLUSION:Despite a significantly deeper corneal DL depth created by accelerated epithelium-off CXL technique compared to accelerated trans-epithelium CXL,there is no significant impact on keratoconus progression.

Bilateral benign reactive lymphoid hyperplasia of the conjunctiva: a case treated with oral doxycycline and review of the literature

Background:To report a case of bilateral benign reactive lymphoid hyperplasia(BRLH)of the conjunctiva treated with oral doxycycline and perform review of the literature evaluating the presentation,treatment and risk of transformation to lymphoma.Case presentation:A case report is described and review of the literature from January 1975 to January 2019 was performed.A 30-year-old man presented with bilateral enlarging fleshy pink medial canthal conjunctival lesions.Incisional biopsy revealed BRLH.Oral doxycycline was initiated(100 mg two times a day)for a total of 2 months.Both lesions decreased in size significantly at the patient’s two-month follow up visit.The residual lesion in the right eye was excised along with an adjacent pterygium and the patient has been free of recurrence for the past 1.5 years.The lesion in the left eye has remained stable in size after cessation of the oral doxycycline.A total of 235 cases of conjunctival BRLH were identified in our literature search.The mean age at diagnosis was 35.2 years(range,5 to 91 years).BRLH lesions were unilateral in 75%of patients and bilateral in 25%of them.Seven patients(2.9%)had a concurrent Epstein-Barr virus(EBV)infection at the time of lesion appearance.The most common treatments were surgical excision(155/235 or 65.9%)and corticosteroids(30/235 or 12.7%),while 14%(33/235)of the patients were observed and 4.6%(11/235)received external beam radiotherapy alone.Recurrence occurred in ten patients(10/235 or 4.2%),of whom five had undergone surgical excision alone,two excision followed by external beam radiotherapy,one excision and oral corticosteroids,one radiotherapy alone and one had been treated with topical corticosteroids.Overall,only 2 of the 235 reported cases(0.8%)developed malignancy,one localized to the conjunctiva and one systemic.Conclusions:Benign reactive lymphoid hyperplasia is one of the lymphoproliferative disorders of the conjunctiva and ocular adnexa.Extensive literature review shows that most cases are treated with surgery,steroids or observation.Oral doxycycline may be considered an alternative non-invasive treatment of BRLH conjunctival lesions.BRLH lesions warrant careful follow up as they can rarely transform into conjunctival or systemic lymphoma.