Epidemiology of Thyroid-stimulating immunoglobulin in Recent Onset Symptomatic Thyroid Eye Disease.

PURPOSE: This study aims to report correlations between thyroid-stimulating immunoglobulin(TSI) and both clinical and radiological parameters in recent-onset symptomatic thyroid eye disease(TED) patients. METHODS: A prospective cohort study of TED patients managed at the Chinese University of Hong Kong from January 2014 to May 2022. Serum TSI levels were determined with the functional assay. Outcomes included the clinical activity score(CAS), marginal reflex distance1(MRD1), extraocular muscle motility restriction(EOMy), exophthalmos, and diplopia. The radiological assessment included cross-sectional areas and signal of extraocular muscles on STIR-sequence MRI. RESULTS: A total of 255(197female) treatment-naïve patients, with an average onset age of 50±14 years, were included. Elevated pre-treatment TSI level was observed in 223(88%) patients. There was a weak positive correlation between TSI and CAS(r=0.28, P=0.000031), MRD1(r=0.17, P=0.0080), and the size of the levator palpebrae superioris/superior rectus complex(r=0.25, P=0.018). No significant correlation existed between TSI and STIR signals. The AUC and optimal cut-off value for clinical active TED were 0.67(95% confidence interval:0.60-0.75) and 284%(Specificity:50%, sensitivity:85%). 64 patients received intravenous methylprednisolone (IVMP) during the study interval, and they had a higher baseline TSI level than those who did not have IVMP(P=0.000044). Serial post-IVMP TSI among the 62 patients showed a significant reduction compared to the baseline level(P<0.001). Both the baseline and post-IVMP TSI levels, and percentages of TSI changes were comparable between patients who responded and non-responded to the first course of IVMP. CONCLUSION: TSI can be a serum biomarker for the diagnosis, prognosis, and treatment response of TED. Further validation should be further warranted.

Investigation of lacrimal gland and extraocular muscle in thyroid eye disease patients with severe subjective dry eye disease: a multiparametric magnetic resonance imaging study.

PURPOSE: To analyze the radiological features of the lacrimal gland (LG) and extraocular muscle (EOM) in thyroid eye disease (TED) patients with severe subjective dry eye disease (DED) using magnetic resonance imaging (MRI) measurements. METHODS: In this cross-sectional study, mechanical ocular exposure, dry eye assessment and MRI data were collected. Patients were classified into non-severe subjective DED group with ocular surface disease index (OSDI) < 33 and severe subjective DED group with OSDI ≥ 33. Linear regression model was applied for comparing the OSDI < 33 and OSDI ≥ 33 group in TED patients. The predictive performance of MRI parameters and models was assessed by receiver operating characteristic curve (ROC) analysis. RESULTS: Consecutive 88 TED patients (176 eyes) were included in this study. In the OSDI < 33 group, 52 TED patients (104 eyes) with a mean clinical activity score (CAS) of 0.63 ± 0.75. In the OSDI ≥ 33 group, there are 36 TED patients (72 eyes), with a mean CAS of 1.50 ± 1.54. The age and sex of the patients were matched between the two groups. The OSDI ≥ 33 group had shorter tear break-up time, larger levator palpebrae superioris / superior rectus (LPS/SR), inferior rectus and lateral rectus, smaller LG, more inflammatory LPS/SR and inferior rectus than OSDI < 33 DED group (P < 0.05). In the linear regression analysis, compare to the OSDI < 33 DED group, the OSDI ≥ 33 group had larger medial rectus cross-sectional area (ß = 0.06, 95%CI: (0.02, 0.10), P = 0.008), larger inferior rectus cross-sectional area (ß = 0.06, 95%CI: (0.00, 0.12), P = 0.048), smaller LG cross-sectional area (ß = -0.14, 95%CI: (-0.25, -0.04), P = 0.008). In the ROC analysis, the area under curve of medial rectus, inferior rectus, LG, and combined model are 0.625, 0.640, 0.661 and 0.716, respectively. CONCLUSION: Multiparametric MRI parameters of the LG and EOM in TED patients with severe subjective DED were significantly altered. Novel models combining the cross-sectional area of LG, medial rectus and inferior rectus showed good predictive performance in TED patients with severe subjective DED.

Diagnostic methods for dysthyroid optic neuropathy: A systematic review and analysis.

Diagnosis of dysthyroid optic neuropathy (DON) typically relies on a set of diagnostic clinical features, including decreased visual acuity, impaired color vision, presence of relative afferent pupillary defect, optic disc swelling and ancillary tests including visual field (VF), pattern visual evoked potential (pVEP), and apical crowding or optic nerve stretching on neuroimaging. We summarize various diagnostic methods to establish or rule out DON. A total of 95 studies (involving 4619 DON eyes) met the inclusion criteria. All of the studies considered clinical features as evidence of DON, while most of the studies confirmed DON diagnosis by combining clinical features with ancillary tests. Forty studies (42.1%) used at least 2 out of the 3 tests (VF, pVEP and neuroimaging) and 13 studies (13.7%) used all 3 tests to diagnose DON. In 64 % of the published studies regarding DON, the diagnostic methods of DON were not specified. It is important to note the limitations of relying solely on clinical features for diagnosing DON. On the other hand, since some eyes with optic neuropathy can be normal in one ancillary test, but abnormal in another, using more than one ancillary test to aid diagnosis is crucial and should be interpreted in correlation with clinical features. We found that the diagnostic methods of DON in most studies involved using a combination of specific clinical features and at least 2 ancillary tests.

Magnetic resonance imaging parameters on lacrimal gland in thyroid eye disease: a systematic review and meta-analysis.

BACKGROUND: Thyroid eye disease is an extrathyroidal manifestation of Graves' disease and is associated with dry eye disease. This is the first systematic review and meta-analysis to evaluate the role of magnetic resonance imaging lacrimal gland parameters in thyroid eye disease diagnosis, activity grading, and therapeutic responses prediction. METHODS: Up to 23 August, 2022, 504 studies from PubMed and Cochrane Library were analyzed. After removing duplicates and imposing selection criteria, nine eligible studies were included. Risk of bias assessment was done. Meta-analyses were performed using random-effect model if heterogeneity was significant. Otherwise, fixed-effect model was used. Main outcome measures include seven structural magnetic resonance imaging parameters (lacrimal gland herniation, maximum axial area, maximum coronal area, maximum axial length, maximum coronal length, maximum axial width, maximum coronal width), and three functional magnetic resonance imaging parameters (diffusion tensor imaging-fractional anisotropy, diffusion tensor imaging-apparent diffusion coefficient or mean diffusivity, diffusion-weighted imaging-apparent diffusion coefficient). RESULTS: Thyroid eye disease showed larger maximum axial area, maximum coronal area, maximum axial length, maximum axial width, maximum coronal width, diffusion tensor imaging-apparent diffusion coefficient/ mean diffusivity, and lower diffusion tensor imaging-fractional anisotropy than controls. Active thyroid eye disease showed larger lacrimal gland herniation, maximum coronal area, diffusion-weighted imaging-apparent diffusion coefficient than inactive. Lacrimal gland dimensional (maximum axial area, maximum coronal area, maximum axial length, maximum axial width, maximum coronal width) and functional parameters (diffusion tensor imaging-apparent diffusion coefficient, diffusion tensor imaging-apparent diffusion coefficient) could be used for diagnosing thyroid eye disease; lacrimal gland herniation, maximum coronal area, and diffusion-weighted imaging-apparent diffusion coefficient for differentiating active from inactive thyroid eye disease; diffusion tensor imaging parameters (diffusion tensor imaging-fractional anisotropy, diffusion tensor imaging-mean diffusivity) and lacrimal gland herniation for helping grading and therapeutic responses prediction respectively. CONCLUSIONS: Magnetic resonance imaging lacrimal gland parameters can detect active thyroid eye disease and differentiate thyroid eye disease from controls. Maximum coronal area is the most effective indicator for thyroid eye disease diagnosis and activity grading. There are inconclusive results showing whether structural or functional lacrimal gland parameters have diagnostic superiority. Future studies are warranted to determine the use of magnetic resonance imaging lacrimal gland parameters in thyroid eye disease.

Investigating the Impact of COVID-19 Infection on Dry Eye Parameters.

PURPOSE: This study aims to compare dry eye parameters before and after COVID-19 infection in dry eye patients. METHODS: We included 44 dry eye patients (88 eyes) from our existing dry eye cohort, with 22 belonging to the post-COVID-19 group due to a prior COVID-19 infection and the other 22 forming the non-COVID-19 group as they had no history of COVID-19. We examined and compared the dry eye parameters of the post-COVID-19 group, including the ocular surface disease index (OSDI), Schirmer's test results (ST), non-invasive Keratography tear break-up time (NIKBUT), lipid layer thickness (LLT), Meibomian gland dysfunction (MGD), and the grading of papillae and follicles, both before and after the COVID-19 infection. We also compared the dry eye parameters difference of the post-COVID-19 group with the non-COVID-19 group. RESULTS: The post-COVID-19 group was comprised of individuals with an average age of 38.36 ± 14.99 years, of which 82% were female. The time interval between the two tests was 16.92 ± 5.40 months, which did not differ significantly from the non-COVID-19 group. Compared to the pre-COVID-19 eyes, the post-COVID-19 eyes showed a significant decrease in the average LLT (52.86 ± 18.00 nm vs. 63.00 ± 22.40 nm, p < 0.001), as well as the maximum LLT (67.89 ± 20.81 nm vs. 78.48 ± 20.55 nm, p < 0.001). The MGD in both the upper (1.75 ± 0.84) and lower eyelids (1.43 ± 0.73) worsened after a COVID-19 infection. Additionally, the grading of papillae was worse following a COVID-19 infection (0.61 ± 0.69 vs. 0.16 ± 0.37, p < 0.001). The multivariate linear regression model revealed a negative association between COVID-19 infection and NIKBUT-average (ß = -2.98, 95%CI: (-5.82, -0.15), p = 0.039), LLT-average (ß = -14.12, 95%CI: (-22.66, -5.59), p = 0.001), and LLT max (ß = -15.65, 95%CI: (-23.09, -8.20), p < 0.001). CONCLUSION: From preliminary results, we concluded that dry eye patients who have been infected with COVID-19 appear to have a more severe dry eye condition, as evidenced by lower LLT, worse papillae and MGD, and shorter NIKBUT. It is important to raise awareness of this potential long-term symptom of COVID-19, especially among existing dry eye patients.

Ocular Surface Changes in Treatment-Naive Thyroid Eye Disease.

OBJECTIVE: To investigate the association of meibomian gland dysfunction (MGD) and ocular surface exposure with tear film instability in untreated thyroid eye disease (TED) patients. METHODS: A cross-sectional study of TED patients from September 2020 to September 2022 was conducted. Ocular surface parameters included ocular surface disease index (OSDI), tear meniscus height (TMH), non-invasive tear break-up time (NITBUT), partial blinking rate, lipid layer thickness (LLT), meibomian gland dropout (meiboscore), Schirmer's test, and corneal punctate epithelial erosions (PEE). Ocular surface exposure was assessed by the margin reflex distances of the upper and lower eyelid (MRD1 and MRD2), the amount of exophthalmos, lateral flare, and lagophthalmos. RESULTS: In total, 152 eyes from 76 TED patients (64 females and 12 males, age 42.99 ± 12.28 years) and 93 eyes from 61 healthy controls (51 females and 10 males, age 43.52 ± 17.93 years) were examined. Compared with control eyes, TED eyes had higher OSDI, TMH, LLT, and PEE; shorter NITBUT; and worse meiboscore (all p < 0.05). They also had larger amounts of exophthalmos, longer MRD1, more lateral flare, and lagophthalmos. Multivariate analysis identified an association of the tear film instability with lagophthalmos (ß = -1.13, 95%CI: -2.08, -0.18) and severe MGD in the lower eyelid (ß = -5.01, 95%CI = -7.59, -2.43). CONCLUSIONS: Dry eye in TED is mainly manifested as evaporative dry eye disease. Severe lower eyelid MGD and worse lagophthalmos were significantly associated with tear film instability in treatment-naive TED patients.

Clinical Significance of Corneal Striae in Thyroid Associated Orbitopathy.

PURPOSE: To elucidate the clinical implications of corneal striae (CS) in thyroid associated orbitopathy (TAO) patients. METHODS: In this cross-sectional study, the presence of CS was confirmed after topical fluorescein staining on a slit lamp for consecutive treatment-naive TAO patients. Orbital parameters, including margin reflex distances, lagophthalmos, exophthalmos, intraocular pressure and radiological measurements, were compared between eyes with and without CS. The largest cross-sectional areas of each rectus muscle were measured by segmenting the T1-weighted (T1W) magnetic resonance images (MRI). The logistic regression analyses were used to evaluate the associations between CS and orbital parameters and rectus muscle measurements. RESULTS: Fifty-three consecutive TAO patients (presenting age 46.47 ± 14.73 years, clinical activity score 1.77 ± 1.25) who had unilateral CS were enrolled. In univariate analysis, both the degree of lagophthalmos and the area of the levator palpebrae superioris-superior rectus complex (LPS/SR) on T1W MRI were significantly larger in CS eyes compared to eyes without CS (p < 0.05). Multivariate analyses showed that CS in TAO patients were significantly associated with the degree of lagophthalmos (OR = 1.75, 95% CI: 1.18-2.61, p < 0.05) and LPS/SR area (OR = 19.27, 95% CI: 1.43-259.32, p < 0.05) but not with the other parameters. CS could predict LPS/SR enlargement and larger lagophthalmos in TAO (p < 0.05). The largest cross-sectional areas of LPS/SR and inferior rectus were positively correlated with clinical activity scores (p < 0.05). CONCLUSIONS: The presence of CS in TAO eye is significantly associated with LPS/SR enlargement and worse lagophthalmos. CS might be evaluated further as a potential ocular surface biomarker to identify upper lid and LPS/SR involvement in TAO.

Myopia incidence and lifestyle changes among school children during the COVID-19 pandemic: a population-based prospective study.

BACKGROUND: The impacts of social restrictions for COVID-19 on children's vision and lifestyle remain unknown. AIMS: To investigate myopia incidence, spherical equivalent refraction (SER) and lifestyle changes among schoolchildren during the COVID-19 pandemic. METHODS: Two separate longitudinal cohorts of children aged 6-8 years in Hong Kong were included. The COVID-19 cohort was recruited at the beginning of the COVID-19 outbreak, whereas the pre-COVID-19 cohort was recruited before the COVID-19 pandemic. All children received ocular examinations, and answered a standardised questionnaire relating to their lifestyle, including time spent on outdoor activities and near work, both at baseline and at follow-up visits. RESULTS: A total of 1793 subjects were recruited, of whom 709 children comprised the COVID-19 cohort with 7.89±2.30 months of follow-up, and 1084 children comprised the pre-COVID-19 cohort with 37.54±3.12 months of follow-up. The overall incidence was 19.44% in the COVID-19 cohort, and 36.57% in pre-COVID-19 cohort. During the COVID-19 pandemic, the change in SER and axial length was -0.50±0.51 D and 0.29±0.35 mm, respectively; the time spent on outdoor activities decreased from 1.27±1.12 to 0.41±0.90 hours/day (p<0.001), while screen time increased from 2.45±2.32 to 6.89±4.42 hours/day (p<0.001). CONCLUSIONS: We showed a potential increase in myopia incidence, significant decrease in outdoor time and increase in screen time among schoolchildren in Hong Kong during the COVID-19 pandemic. Our results serve to warn eye care professionals, and also policy makers, educators and parents, that collective efforts are needed to prevent childhood myopia-a potential public health crisis as a result of COVID-19.

An update on endoscopic mechanical and powered dacryocystorhinostomy in acute dacryocystitis and lacrimal abscess.

PURPOSE: To provide a brief review of the literature on the utility and outcomes of endoscopic dacryocystorhinostomy (DCR) in patients with acute dacryocystitis (ADC) and lacrimal abscess. METHODS: The authors performed a PubMed search of all articles published in English on endoscopic powered or mechanical DCR performed during the stage of acute dacryocystitis. Data captured include demographics, clinical presentations, time interval to surgery, intraoperative challenges, post-operative course, complications and outcomes. Specific emphasis was laid on addressing the intra-operative challenges and post-operative outcomes. RESULTS: Increased intra-operative bleeding is a common finding. The use of mitomycin C and silicone intubation are not uncommon and are not reported to have negative influence on the outcomes of surgery. The general consensus is to initiate antibiotics immediately or a day before surgery and continue them in the post-operative period. Symptomatic pain relief was achieved very early (immediate to <3 days) and complete resolution was usually achieved in a week's time. The overall anatomical success rates varied from 81.8 to 96.2% and functional success from 72.7 to 96.2%. Cicatricial closure of the ostium was a common cause of failure. CONCLUSION: Primary endoscopic DCR appears to be an effective modality in the management of ADC and lacrimal abscess, and results in a rapid resolution of inflammation while achieving comparable surgical success with a traditional approach of conservative management with or without drainage and 2nd stage external DCR.

Elevated bone morphogenic protein 4 expression implicated in site-specific adipogenesis in thyroid associated orbitopathy.

Periorbital adipose tissue expansion is a key pathological change in thyroid associated orbitopathy (TAO). Bone morphogenic protein 4 (BMP4) is instrumental in adipogenesis. We compared site-specific BMP4 expression and its effect on adipogenesis using donor-matched adipose tissue-derived stromal cells (ADSC) from TAO patients. In this study, ADSC were generated from periorbital (eyelid, orbital) and subcutaneous (abdominal) adipose tissue. BMP4 expression was characterized by RT-PCR and immunofluorescent staining and compared among ADSC from the three anatomic depots. Effects on adipogenesis after knocking down endogenous BMP4 were quantified by adipogenic markers PPARγ and perilipin. Exogenous BMP4 protein was added after BMP4 knockdown to study the role of BMP4 in adipogenesis. Our results showed that BMP4 staining in periorbital adipose tissue was stronger than those in subcutaneous. BMP4 mRNA expression was higher in eyelid (4.4-2489.4-fold) and orbital (6.9-1811-fold) than that of subcutaneous ADSC, whereas expression fell during induced adipogenesis. After BMP4 knockdown, both adipogenic markers PPARγ (eyelid: 1.7-fold, p = 0.038; orbital: 1.4-fold, p = 0.126) and perilipin (eyelid:1.7-fold, p = 0.001; orbital:2.6-fold, p = 0.066) increased in periorbital ADSC upon induction. These increased expression fell after adding exogenous BMP4 protein. Our findings demonstrated higher BMP4 expression was found in periorbital ADSC and adipose tissue compared to donor-matched subcutaneous counterparts, which fell during adipogenic induction. Knocking down BMP4 expression further enhanced adipogenesis in periorbital ADSC. This effect was reversed by adding exogenous BMP4 protein. We suggested a novel role of BMP4 in modulating site-specific adipogenesis in TAO patients.

Depot-specific characteristics of adipose tissue-derived stromal cells in thyroid-associated orbitopathy.

BACKGROUND: Thyroid-associated orbitopathy (TAO) causes inflammatory fibroproliferation of periocular connective tissues. We compared adipose tissue-derived stem/stromal cells (ADSCs) from three adipose depots of each patient with TAO on mesenchymal, myofibrogenic, adipogenic properties and associated hyaluronan (HA) synthesis. METHODS: ADSCs were generated from periocular (eyelid, orbital) and subcutaneous (abdominal) adipose tissues of three patients with TAO. Mesenchymal markers were characterised by reverse transcription-PCR and immunofluorescent staining. A 3-week adipogenic induction was evaluated by Nile red staining and quantitative PCR (qPCR) of peroxisome proliferator-activated receptor (PPARγ), adiponectin and hyaluronan synthase (HAS)-2. A 7-day myofibrogenic induction was assayed by immunofluorescent staining and qPCR of α-smooth muscle actin (α-SMA). RESULTS: ADSCs from all depots expressed similar levels of mesenchymal markers CD44, CD90 and CD105 (p=0.288, p=0.43 and p=0.837, respectively). After adipogenic induction, intracellular lipid increased for more than 32% and PPARγ mRNA showed more than twofold increase from all three depots. However, adiponectin and HAS-2 mRNA levels were significantly higher in the eyelid and orbital ADSCs than those from the subcutaneous ADSCs after induction (2.4×107, 3.9×106 folds vs below detection limit; 63.3-fold, 26.1-fold, vs 33% reduction, respectively; all p=0.002). Significantly more myofibroblasts and higher mRNA level of α-SMA were obtained from the orbital and eyelid compared with the subcutaneous ADSCs during myofibrogenic induction (80.2%, 70.6% vs 29.3%; 30.2-fold, 24.2-fold vs 1.7-fold, respectively; all p=0.002). CONCLUSION: ADSCs from different adipose depots of the same donors exhibited similar mesenchymal phenotypes but differed significantly in adipogenic, myofibrogenic potentials and associated HA synthesis. These depot-specific characteristics of ADSCs may contribute to site-specific adipose tissue involvement in TAO.

Lacrimal gland abscess in children: Two case reports and literature review.

Acute suppurative bacterial dacryoadenitis (ASBD) with abscess formation is rarely seen in clinical practice. A retrospective review of medical records in the past 8 years identified two unilateral cases in children, one developed presumably after methicillin-sensitive Staphylococcus aureus (MSSA) conjunctivitis and the other due to community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infection. Computerized tomography scans showed globe indentation by the enlarged lacrimal glands with rim-enhancing lesions. After failing to respond to intravenous antibiotics, both abscesses resolved promptly with surgical drainage without any long-term sequelae.

Antagonist of GH-releasing hormone receptors alleviates experimental ocular inflammation.

Disruptions in immunity and occurrence of inflammation cause many eye diseases. The growth hormone-releasing hormone-growth hormone-insulin-like growth factor-1 (GHRH-GH-IGF1) axis exerts regulatory effects on the immune system. Its involvement in ocular inflammation remains to be investigated. Here we studied this signaling in endotoxin-induced uveitis (EIU) generated by LPS. The increase in GHRH receptor (GHRH-R) protein levels was parallel to the increase in mRNA levels of pituitary-specific transcription factor-1, GHRH-R splice variant 1, GHRH, and GH following LPS insult. Elevation of GHRH-R and GH receptor was localized on the epithelium of the iris and ciliary body, and GHRH-R was confined to the infiltrating macrophages and leukocytes in aqueous humor but not to those in stroma. Treatment with GHRH-R antagonist decreased LPS-stimulated surges of GH and IGF1 in aqueous humor and alleviated inflammation by reducing the infiltration of macrophages and leukocytes and the production of TNF-α, IL-1ß, and monocyte chemotactic protein-1. Our results indicate that inflammation in the iris and ciliary body involves the activation of GHRH signaling, which affects the recruitment of immune cells and the production of proinflammatory mediators that contribute to EIU pathogenesis. Moreover, the results suggest that GHRH-R antagonists are potential therapeutic agents for the treatment of acute ocular inflammation.

Lateral canthal surgery.

The lateral canthus is a delicate and complicated three-dimensional structure with function relevant to the health of the ocular surface. Dysfunction of the lateral canthus, due to aging changes or iatrogenic trauma, results in ocular morbidity ranging from chronic irritation to tearing to recalcitrant keratopathy. From an aesthetic standpoint, symmetric, normally positioned lateral canthi are cornerstones of youthful periorbital appearance, disruption of which leads to cosmetically significant deformity or asymmetry. Reconstruction of the lateral canthus is important in the rehabilitation of the aging eyelid and an unfortunate necessity after failed lateral canthal surgery. The common methods for improving or maintaining position, tone, and shape of the lower eyelid and lateral canthus use tightening or shortening the lower eyelid horizontally, keeping the canthal angle in an appropriate vertical level, and hugging the ocular surface. Many techniques have been described for the reconstruction of the lateral canthus in functional conditions or for aesthetic purposes. These methods have met with varying success. In this article, we begin with a discussion of the anatomy and physiology of the lateral canthus, followed by clinical examples of lateral canthal abnormalities and underlying pathophysiologies. A review of surgical options for the lateral canthus is presented with concluding remarks on postoperative complications.

Optic disc measurements in myopia with optical coherence tomography and confocal scanning laser ophthalmoscopy.

PURPOSE: To evaluate the relationships between optic disc measurements, obtained by an optical coherence tomograph and a confocal scanning laser ophthalmoscope, and myopia. METHODS: One hundred thirty-three eyes from 133 healthy subjects with mean spherical equivalent -6.0 +/- 4.2 D (range, -13.13 to +3.25 D) were analyzed. Optic disc measurements including disc area, rim area, cup area, cup-to-disc area, and vertical and horizontal ratios were obtained with an optical coherence tomograph (StratusOCT; Carl Zeiss Meditec Inc., Dublin, CA) and a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph, HRT 3; Heidelberg Engineering, GmbH, Dossenheim, Germany). The modified axial length method derived from prior published work was used to correct the OCT measurements for ocular magnification. Bland-Altman plots were used to evaluate the agreement for each optic disc parameter. Associations between optic disc area and axial length/spherical equivalent were evaluated by linear regression analysis. RESULTS: Disc area increased with the axial length/negative spherical equivalent in the HRT and the corrected OCT measurements although opposite directions of associations were found when the OCT measurements were not corrected for magnification. The difference of the corrected OCT and HRT disc area (corrected OCT disc area minus HRT disc area) was correlated with the axial length (r = 0.195, P = 0.025). When the ametropia was limited to -8.0 to +4.0 D, the correlations became insignificant in the HRT. Using the corrected OCT measurements, disc area, rim area, and cup area, cup-to-disc area, and cup-to-disc horizontal and vertical ratios were significantly larger than those measured by the HRT, with a span of 95% limits of agreement at 1.99, 1.33, and 1.86 mm(2) for the areas, 0.34, 0.53, and 0.58 for the ratios, respectively. CONCLUSIONS: While optic disc area generally increased with the axial length and myopic refraction, the HRT measurements demonstrated that optic disc size was largely independent of axial length and refractive error between -8 and +4 D. OCT may overestimate optic disc size in myopic eyes and results in poor agreement between the two instruments.

Alignment artifacts in optical coherence tomography analyzed images.

PURPOSE: To compare retinal thickness and retinal height of the original scanned optical coherence tomography (OCT) images with those of the same images after automated retinal thickness analysis. DESIGN: Cross-sectional study. PARTICIPANTS: Thirty normal eyes, 20 eyes with neovascular age-related macular degeneration (AMD), 20 with central serous chorioretinopathy (CSC), 20 with macular holes, and 20 with non-AMD related macular edema from 110 subjects were selected randomly from an OCT database. One of the 6 macular scans in each eye was chosen randomly for analysis. METHODS: Two sets of OCT images--original images and analyzed images (after retinal thickness [single eye] analysis)--in each eye were exported for retinal thickness or retinal height measurement. Comparisons of retinal thickness or retinal height at selected locations were performed. MAIN OUTCOME MEASURES: Retinal thickness (defined as the distance between the anterior boundary of the retinal nerve fiber layer [RNFL] and posterior boundary of the photoreceptor layer) and retinal height (defined as the distance between the anterior boundary of the RNFL and baseline level of the anterior boundary of the retinal pigment epithelium [RPE]). Retinal height was measured when there was detachment of neurosensory retina or RPE. RESULTS: No significant difference in retinal thickness was observed between the original and the analyzed OCT images in normal eyes and in eyes with macular holes or non-AMD related macular edema. However, OCT-analyzed images demonstrated retinal thickness or retinal height measurements in eyes with CSC or neovascular AMD significantly lower than the corresponding measurements in the original images (all with Ps< or =0.001, Wilcoxon signed rank test). In the groups of neovascular AMD and CSC, Bland-Altman plots revealed mean differences of 124 mum (95% limits of agreement between -65.5 and 313.6) and 84.4 mum (95% limits of agreement between -178.0 and 346.8), respectively, between the original and analyzed retinal measurements. CONCLUSIONS: Retinal thickness and retinal height could be underestimated in patients with CSC or neovascular AMD after retinal thickness analysis in Stratus OCT when either automatic measurements or manual caliper-assisted measurements are performed on the analyzed images. We recommend exporting the original scanned OCT images for retinal thickness and retinal height measurement in patients with CSC or neovascular AMD.