Revisiting Pentacam Parameters in the Diagnosis of Subclinical and Mild Keratoconus Based on Different Grading System Definitions

Objectives: To retest the performance of Pentacam parameters in the detection of eyes with subclinical keratoconus (KC) and mild KC based on different definitions from the Amsler-Krumeich (AK), Collaborative Longitudinal Evaluation of Keratoconus (CLEK), and ABCD systems. Materials and Methods: This cross-sectional university-based study comprised 24 eyes with subclinical KC, 144 eyes with mild KC (based on AK in 101 eyes, CLEK in 28 eyes, and ABCD in 15 eyes), and 70 controls. Diagnostic ability of the thinnest point (TP) pachymetry, KISA% index, inferior-superior asymmetry, corneal aberrations, Pentacam indices, front/back elevations, pachymetric progression index, Ambrósio-Relational Thickness (ARTmax), and Belin/Ambrósio Enhanced Ectasia Display scores (Df, Db, Dp, Dt, Da, and D-final) were evaluated. Results: ARTmax (83.3% sensitivity/74.3% specificity) had the highest ability in distinguishing subclinical KC from normal, followed by TP pachymetry, Dt, and Da. D-final showed excellent sensitivity/specificity in mild KC diagnosis based on AK (98%/100%) and CLEK (97.4%/100%) descriptions. In the mild KC-ABCD group, index of vertical asymmetry accurately detected all eyes with mild KC and 97.1% of the controls. Conclusion: This study points out the gray zone in the detection of eyes with subclinical and mild KC due to overlapping terminology and grading criteria. Pentacam parameters seem to have modest capability in subclinical KC detection, indicating the necessity for additional diagnostic modalities. However, eyes with mild KC can be diagnosed with high accuracy using Pentacam parameters, although the strongest parameters may vary according to the definition of "mild KC." Nevertheless, uniform and definitive criteria for subclinical and clinical KC classification are required for a diagnostic and therapeutic consensus in KC.

Measurements of scleral thickness and corneal optic densitometry in patients with systemic lupus erythematosus.

BACKGROUND: This study aimed to evaluate the scleral thickness and corneal parameters of patients with systemic lupus erythematosus (SLE). METHODS: Forty-seven eyes of 47 SLE patients and 44 eyes of healthy controls were included in this cross-sectional study. Anterior segment optical coherence tomography (AS-OCT) was used to measure the corneal and scleral thickness. Scleral thickness (ST) was measured based upon the segmentation at 1000 to 5000 µm from the scleral spur. Pentacam HR was used to measure corneal parameters. RESULTS: There was no statistically significant difference between SLE group and control group according to age and sex (P > .05). The ST measurements at all distances from scleral spur were found to be thicker in patients with SLE (P < .05). Central corneal thickness (CCT), cornea volume (CV), corneal densitometry (CD), and peripheral corneal thickness (PCT) measurements were similar between the groups (P > .05). CONCLUSION: ST was thicker in SLE patients compared with healthy controls. AS-OCT seems helpful in selecting optimal sites for pharmaceutical or surgical intervention in SLE patients, since it shows thickness variations in anterior sclera.

Effect of microalbuminuria on corneal endothelium in patients with diabetes without retinopathy.

BACKGROUND: The aim of this study was to investigate the effect of microalbuminuria on corneal endothelium in patients with diabetes without retinopathy. METHODS: This cross-sectional study comprised 100 patients with type 2 diabetes mellitus (DM) without diabetic retinopathy and 92 control subjects without diabetes. Forty-five patients had microalbuminuria and 55 subjects were microalbuminuria negative. Endothelial measurements were obtained using specular microscopy. Endothelial cell density, average area, co-efficient of variation, maximum area, minimum area, hexagonality and corneal thickness were compared between the groups on the basis of microalbuminuria, DM duration and medication, HbA1c , body mass index, serum lipid and protein profiles, hypertension and hyperlipidaemia diagnosis. RESULTS: There were no significant differences in age, gender, endothelial cell density, average area, co-efficients of variation, maximum area, minimum area, hexagonality or corneal thickness among the microalbuminuria positive, microalbuminuria negative and control groups (p > 0.05). However, microalbuminuria positive patients had lower high-density lipoprotein levels than the microalbuminuria negative patients (p = 0.042). DM and control groups showed similar endothelial measurements (p > 0.05). Patients with a HbA1c > 7 per cent (53 mmol/mol) had lower hexagonality value (p = 0.039) than in the subjects with a HbA1c ≤ 7 per cent. No significant differences were found in endothelial parameters when groups were compared based on DM duration, medication and co-morbidities. CONCLUSIONS: Microalbuminuria positive and negative patients with DM without retinopathy seem to have similar corneal endothelial measurements with controls. However, patients with a HbA1c > 7 per cent should be monitored for deterioration in corneal endothelial cell morphology even without diabetic retinopathy, which might be critical prior to anterior segment surgery.

Early retinal neurodegeneration in preclinical diabetic retinopathy: a multifactorial investigation.

BACKGROUND/OBJECTIVES: To investigate effects of microalbuminuria (MA), diabetes duration, glycosylated haemoglobin (HbA1c) level, hypertension (HT) and/or hyperlipidaemia (HL) coexistence on retinal layers in diabetic patients without diabetic retinopathy (DR) using spectral-domain optical coherence tomography (SD-OCT). SUBJECTS/METHODS: This cross-sectional study involved 95 (45 had MA and 50 had no MA) patients with type 2 diabetes mellitus (DM) without DR and 91 age- and gender-matched non-diabetic controls. Macular and peripapillary SD-OCT measurements (Heidelberg Engineering GmbH, Heidelberg, Germany), DM duration, HbA1c levels and presence of HT and/or HL were used for statistical analyses. RESULTS: The MA (+), MA (-) and control groups had similar age and gender distribution (p > 0.05). The differences in SD-OCT measurements among the MA (+), MA (-) and control groups were insignificant (p > 0.05). However, diabetic patients (n = 95) had significantly thinner inferior-temporal peripapillary retinal nerve fibre layer (RNFL) (p = 0.042) than in the controls (n = 91). Superior peripapillary RNFL was significantly thinner in patients with an HbA1c level > 7% (p = 0.049). However, 3 mm-nasal, temporal and superior perifoveal thicknesses were significantly lower in patients with DM duration over 10 years (p < 0.05). HT and/or HL coexistence did not lead a significant difference in SD-OCT parameters among the groups. CONCLUSIONS: In diabetic patients without DR, peripapillary inferior-temporal RNFL thinning might be an early sign of neuroretinal degeneration and it seems to be independent from vascular endothelial damage (MA). Poor metabolic control appears to lead superior peripapillary RNFL thinning, while perifoveal thicknesses tend to decrease with longer DM duration.

Evaluation of corneal layers and anterior sclera in patients with primary Sjögren's syndrome.

PURPOSE: We aimed to compare the thickness of anterior sclera, corneal layers, and pre-ocular tear film between patients with primary Sjögren's syndrome and healthy individuals. METHODS: Fifty-one patients with primary Sjögren's syndrome and 41 healthy control participants were recruited in this cross-sectional and comparative study. The thickness of the pre-ocular tear film, corneal epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium were measured on the corneal apex. Anterior scleral thickness was measured at distances of 1 mm and 3 mm from the limbus. The anterior segment module of spectral-domain optical coherence tomography was used to measure thicknesses of pre-ocular tear film, corneal layers, and anterior sclera. RESULTS: Tear film thickness, Schirmer's test, and tear break up time values were significantly lower in the Sjögren's disease group than in the healthy controls (p<0.05). The thickness measurements of corneal layers and sclera were similar between the groups. Tear film thickness was moderately correlated with the Schirmer's test results (r=0.34, p=0.001), but there was no correlation between the Schirmer's test results and tear break up time (r=0.18, p=0.09). CONCLUSIONS: Pre-ocular tear film, as measured by anterior segment optical coherence tomography, was thinner in patients with primary Sjögren's syndrome than in the healthy controls. The thicknesses of corneal layers and anterior sclera were similar between the groups.