OCT Measurements Research Articles

Attenuation of the retinal nerve fibre layer and reduced retinal function assessed by optical coherence tomography and full‐field electroretinography in patients exposed to vigabatrin medication

To investigate the clinical value of assessment of peripapillary retinal nerve fibre layer (RNFL) thickness with OCT in addition to the evaluation of retinal function measured by full-field electroretinography (ff-ERG) in patients with suspected vigabatrin (VGB)-attributed visual field defects. Visual fields from adult patients in our clinical follow-up program for VGB medication were analysed. Twelve patients with suspected VGB-attributed visual field defects were selected for the study. They were re-examined with computerized kinetic perimetry, ff-ERG and OCT (2D circle scan). Constricted visual fields were found in all patients. Comparative analysis of ff-ERG parameters showed reduced b-wave amplitudes for the isolated and the combined rod and cone responses (p < 0.0001). The a-wave, reflecting photoreceptor activity, was reduced (p = 0.001), as well as the summed amplitude of oscillatory potentials (p = 0.029), corresponding to inner retinal function. OCT measurements demonstrated attenuation of the RNFL in nine of 12 patients, most frequently superiorly and/or inferiorly. No temporal attenuation was found. Significant positive correlations were found between the total averaged RNFL thickness, superior and inferior RNFL thickness and reduced ff-ERG parameters. Positive correlations were also found between RNFL thickness and isopter areas. OCT measurements can detect attenuation of the RNFL in patients exposed to VGB medication. RNFL thickness correlates with reduced ff-ERG parameters and isopter areas of constricted visual fields, indicating that VGB is retino-toxic on several levels, from photoreceptors to ganglion cells. The study also supports previous studies, suggesting that OCT measurement of the RNFL thickness may be of clinical value in monitoring patients on vigabatrin therapy.

Changes in Anterior Segment Morphology after Intravitreal Injection of Bevacizumab and Bevacizumab–triamcinolone Acetate Combination

To evaluate the effects of 2 different amounts of commonly used intravitreal agents on anterior segment morphology in conjunction with intraocular pressure (IOP) changes. Two groups of 46 patients who received intravitreal injection of bevacizumab (group 1, 0.05 mL) or bevacizumab-triamcinolone acetate (TA) combination (group 2, 0.1 mL) were included in this prospective study. All patients underwent anterior segment optical coherence tomography (AS-OCT) imaging with Visante OCT and IOP measurement before and at 5 minutes, 1 hour, and 3 hours after injection. Anterior chamber depth (ACD), angle-opening distance (AOD 500-750), trabecular-iris space area (TISA 500-750), and anterior chamber angle (ACA) were measured. Results were compared between groups and measurement time points. The mean change in IOP showed significant difference between baseline and first measurements after the injection in group 1 and group 2 (p = 0.012, p = 0.008, respectively). There was a statistically significant difference from baseline in ACD at the first and second measurements in group 2 (p = 0.005, p = 0.018, respectively). All angle parameters showed insignificant decrease from baseline at all measurement time points in both groups (p>0.05 for each). The difference of angle parameters after injection was not statistically significant between the groups (p>0.05 for each). Intravitreal injection of bevacizumab (0.05 mL) or bevacizumab-TA combination (0.1 mL) caused a change in anterior segment configuration determined by AS-OCT. The changes in anterior chamber parameters returned to baseline values with the normalization of IOP values after the first few minutes of injection.

Correlations between Spectral-Domain OCT Measurements and Visual Acuity in Cystoid Macular Edema Associated with Retinitis Pigmentosa

To evaluate the characteristics of spectral-domain optical coherence tomography (SD-OCT) findings associated with visual outcome and compare OCT measurements according to presence of cystoid macular edema (CME) in retinitis pigmentosa (RP) patients. Patients with typical RP who underwent SD-OCT were included. We compared OCT measurements such as central retinal thickness (CRT), photoreceptor thickness, and photoreceptor inner segment/outer segment (IS/OS) junctional status at the fovea between the CME and non-CME groups. Also, correlations between best-corrected visual acuity (BCVA) and each parameter were determined. Among a total of 220 eyes in 128 RP patients, 46 eyes of 30 patients (20.9%) had CME. CRT was 303.1 ± 81.8 μm and 209.2 ± 46.8 μm in the CME and non-CME groups, respectively (P < 0.001). BCVA did not differ between the two groups (P = 0.690). However, among a subgroup with unilateral CME, BCVA was significantly worse in CME eyes than in the fellow eyes (P = 0.046). In the CME group, eyes with increased CRT showed worse BCVA (P = 0.010). Among 12 eyes with severe CME, defined as 350 μm or more CRT, 10 (83.3%) showed an absent IS/OS junction. In the non-CME group, in contrast, eyes with decreased CRT showed worse BCVA (P < 0.001). In both groups, severe IS/OS disruption was correlated with worse BCVA (P < 0.001). The risk of IS/OS disruption was higher in the CME group (P = 0.016). The presence of CME in RP patients was not necessarily correlated with loss of visual acuity. In eyes with CME, however, severe CME was strongly correlated with IS/OS disruption and visual impairment. Thus, severe CME seemed to be a predictor of poor visual outcome in RP patients.

Structure-Function Relationship and Diagnostic Value of RNFL Area Index Compared With Circumpapillary RNFL Thickness by Spectral-Domain OCT

The purpose of the study was to evaluate the structure-function relationship and diagnostic value of retinal nerve fiber layer (RNFL) Area Index from the RNFL thickness deviation map of Cirrus SD-OCT. : A total of 84 normal control eyes, 88 preperimetric eyes, and 146 perimetric glaucoma eyes were analyzed. The area of the RNFL defect in the RNFL thickness deviation map was expressed as RNFL Area Index: 1-[area of superpixels coded in red/(6×6-optic disc area)]. The diagnostic performance of RNFL Area Index and that of circumpapillary RNFL thickness were compared with the area under the receiver operating characteristic curve. Regression analysis was performed with the OCT measurements and the mean retinal sensitivity of the corresponding fields. : The RNFL Area Index was 96.63±14.22%, 89.89±14.54%, and 81.65±17.11% in the control, preperimetric, and perimetric glaucoma group. The RNFL Area Index had the largest area under the receiver operating characteristic curve to discriminate preperimetric and perimetric glaucoma from normal eyes. The RNFL Area Index showed a strong correlation with circumpapillary RNFL thicknesses in perimetric glaucoma, however, only modest correlation was shown in preperimetric glaucoma. In preperimetric glaucoma, the RNFL Area Index had the strongest associations with mean retinal sensitivity and it was significantly different from those of circumpapillary RNFL thicknesses. : The RNFL Area Index showed better diagnostic performance for glaucoma detection and stronger structure-function relationships in preperimetric glaucoma. The RNFL thickness deviation map of Cirrus SD-OCT may be useful to correlate with functional loss in early glaucomatous eyes.

Effects of 30-Day Head-Down Bed Rest on Ocular Structures and Visual Function in a Healthy Subject

We report ocular changes occurring in a healthy human subject enrolled in a bed rest (BR) study designed to replicate the effects of a low-gravity environment. A 25-yr-old Caucasian man spent 30 consecutive days in a 6 degrees head-down tilt (HDT) position at the NASA Flight Analogs Research Unit. Comprehensive ophthalmologic exams, optic disc stereo-photography, standard automated perimetry (SAP), and optic disc Spectralis OCT scans were performed at baseline, immediately post-BR (BR+0), and 6 mo post-BR. changes in best-corrected visual acuity, intraocular pressure (IOP), cycloplegic refraction, SAP, and Spectralis OCT measures. At BR+0 KIOP was 11 and 10 mmHg in the right (OD) and left eye (OS), respectively (a bilateral 4-mmHg decrease compared to baseline); SAP documented a possible bilateral symmetrical inferior scotoma; Spectralis OCT showed an average 19.4 microm (+5.2%) increase in peripapillary retinal thickness, and an average 0.03 mm3 (+5.0%) increase in peripapillary retinal volume bilaterally. However, there were no clinically detectable signs of optic disc edema. At 6 mo post-BR, IOP was 13 and 14 mmHg in OD and OS, respectively, and the scotoma had resolved. Spectralis OCT measurements matched the ones recorded at baseline. In this subject, a reduction in IOP associated with subtle structural and functional changes compared to baseline were documented after prolonged head-down BR. These changes may be related to cephalad fluid shifts in response to tilt. Further studies should clarify whether decreased translaminar pressure (i.e., the difference between IOP and intracranial pressure) may be responsible for these findings.

Multicenter Spanish study of spectral‐domain optical coherence tomography in normal children

To compile a multicenter normative database of retinal nerve fibre layer (RNFL) and macular thicknesses and macular volume values in healthy Caucasian children 4-17 years using spectral-domain optical coherence tomography (SD-OCT). To analyse variations in the OCT measurements as a function of age, sex, refraction, and axial length (AL). An observational, multicenter and cross-sectional study among 301 healthy Caucasian children recruited at three Spanish centres was performed. To compile the database, each child underwent a dilated eye examination and a cycloplegic refraction, five AL measurements (IOL Master; Carl Zeiss Meditec, Dublin, CA, USA), five OCT scans with Cirrus OCT: three peripapillary RNFL scans (Optic Disc Cube 200X200 protocol) and two macular scans (Macular Cube 512X128 protocol). One eye of each subject was selected randomly for analysis. Two hundred eighty-three children (117 boys, 41.34%; 166 girls, 58.66%) were included in this study. The mean age of the children was 9.58 ± 3.12 years (range, 4-17). The mean SE was +0.63 ± 1.65 D; (range, -4.88 to +5.25). The mean AL was 22.94 ± 1.10 mm (range, 20.10-26.27). The mean global RNFL thickness was 97.40 ± 9.0 μm (range, 77-121.7 μm). Multivariate analysis showed a positive correlation between the RNFL and spherical equivalent (SE) (p = 0.014). The mean central macular thickness was 253.85 ± 19.76 μm, the average thickness 283.62 ± 14.08 μm, and the mean macular volume 10.22 ± 0.49 μm(3) . Multivariate analysis showed a positive correlation between central macular thickness and age (p < 0.001). Boys had a significantly thicker central macula than girls (p < 0.001). Normative paediatric SD-OCT data might facilitate use of SD-OCT for assessing childhood ophthalmic diseases. This study provides a multicenter paediatric normative database of SD-OCT peripapillary RNFL and macular data.

Retroprosthetic Membrane and Risk of Sterile Keratolysis in Patients With Type I Boston Keratoprosthesis

To evaluate whether retro-backplate retroprosthetic membrane is correlated with risk of melt in patients with a type I Boston Keratoprosthesis (KPro). Retrospective, observational case series. Study of 50 eyes of 47 patients with type I Boston KPro and postoperative anterior segment optical coherence tomography (AS OCT) imaging performed at the University of Illinois at Chicago. Main outcome measures were presence of retro-backplate membrane and development of melt requiring explantation. For eyes with melt, membrane thickness was measured using the AS OCT images obtained at the last visit before melt occurred. For eyes without melt, the last available AS OCT images were used for measurement. AS OCT evidence of a retro-backplate membrane was observed in 100% of eyes that melted and in 34.1% of eyes that did not (P = .0034; risk ratio, 2.9; 95% confidence interval, 1.9 to 4.4). Retro-backplate membrane thickness in the melt group was 278 μm versus 193 μm in the nonmelt group (P = .025). The retro-backplate portion of a retroprosthetic membrane is to be differentiated from the retro-optic portion seen at the slit lamp. The retro-backplate membrane as shown by AS OCT imaging is correlated with an increased risk of sterile keratolysis, possibly because of impedance of nutritional support from the aqueous humor. Further studies are needed to better standardize the AS OCT measurements of retro-backplate membranes as well as to identify early interventions to prevent progression of thin membranes once identified on AS OCT.

Utility of Anterior Segment OCT Measurements for Predicting Severe Eye Pressure Increase after Intravitreal Dexamethasone Implant

Background/aims: To assess the utility of non-contact anterior segment ocular coherence tomography (AS-OCT) measurement of the angle recess width (AR) to predict eyes prone to intraocular pressure (IOP) spikes after injection of intravitreal dexamethasone implant in patients with CRVO and BRVO. Methods: Cohort study with fellow-eye control of 34 patients with gonioscopically open angles and RVO undergoing intravitreal injection of dexamethasone implant (Ozurdex). All participants received pre-injection AS-OCT in both eyes using spectral domain Cirrus OCT. Independent masked assessors measured the AR width using electronic imaging calipers. IOP was monitored prior to implant placement, and monthly for 6 months thereafter. Comparisons between AR width and degree of steroid response, phakic status, gender, and prior history of glaucoma were analyzed. Results: Seven eyes (20%) developed severe IOP spikes (IOP ≥ 30 mmHg). There was a highly significant (p=0.0085) difference in angle recess width between severe responders (175.0 ± 27.1 μm) and those eyes with less severe response (272.9 ± 24.3 μm). There was also strong correlation between the AR width in study and fellow eyes (mean 248.1 ± 19.8 vs. 261.9 ± 22.6 μm; R2=0.67). Conclusions: This study reaffirms the potential utility of AS-OCT measurement of AR width as a practical means for helping identify eyes at high risk of ocular hypertension after intravitreal corticosteroid administration.

Integrated-optics-based swept-source optical coherence tomography

We designed, fabricated, and characterized an integrated-optics-based swept-source optical coherence tomography (SS-OCT) system in TriPleX technology. An external 1300 nm swept source is coupled to the chip, which contains waveguide structures for interferometric depth ranging and balanced detection. The complete OCT chip has a footprint of 0.4 cm × 1.8 cm. Light from the chip is focused onto the sample using an aspheric lens; the lateral resolution is 21±1 μm. OCT measurements, performed with a moveable mirror, demonstrate a sensitivity of -80 dB and imaging up to the maximum depth of 5.09 mm. Corrected for dispersion, the measured OCT axial resolution of 12.7±0.5 μm is in good agreement with the bandwidth limited resolution. Finally, we demonstrate cross-sectional OCT imaging of a multilayered tissue phantom over the whole depth range with the integrated-optics-based SS-OCT system.

Correlation between multifocal pattern electroretinography and Fourier-domain OCT in eyes with temporal hemianopia from chiasmal compression

To evaluate the correlation between multifocal pattern electroretinography (mfPERG) and Fourier-domain optical coherence tomography (FD-OCT) with regard to macular and retinal nerve fiber layer (RNFL) thickness in eyes with temporal hemianopia from chiasmal compression. Twenty-five eyes from 25 patients with permanent temporal visual field defects from chiasmal compression and 25 healthy eyes were submitted to mfPERG using a stimulus pattern of 19 rectangles, standard automated perimetry and FD-OCT measurements. The mfPERG response was determined for groups of three rectangles for the nasal and temporal hemifields and for each quadrant. Macular thickness measurements were registered according to an overlaid OCT-generated checkerboard with 36 checks and averaged for the central area, and for each scanned quadrant and hemifield. RNFL thickness was determined for all twelve 30-degree segments around the disc, and averaged for the segments corresponding to the 6, 7, 8, 9, 10, 11 and 12 o'clock position. Correlations were verified with Pearson's correlation coefficients and linear regression analysis. Both mfPERG amplitudes and OCT measurements were significantly smaller in eyes with temporal visual field defects than in normals. A significant and strong correlation was found between most mfPERG and macular or RNFL thickness OCT parameters. mfPERG amplitudes and OCT measurements are significantly correlated in patients with chiasmal compression. Both technologies can quantify neuronal loss and, if used in combination, may help clarify structure-function relationships in this patient population.

Quantification of axonal loss in pseudotumor cerebri syndrome using macular thickness measurements with frequency domain‐OCT

AbstractPurpose To evaluate the ability of fourier domain‐optical coherence tomography (FD‐OCT)‐measured macular thickness parameters to differentiate between eyes with chronic papilledema from pseudotumor cerebri (PTC) and healthy eyes and its relationship with visual field (VF) loss on standard automated perimetry (SAP).Methods Fifty‐five eyes from 30 patients with PTC syndrome and 70 eyes from 35 normal controls underwent FD‐OCT (3D OCT‐1000, Topcon) scanning and ophthalmic evaluation including SAP using Humphrey perimetry. All patients had been submitted to previous treatment with clinically resolved papilledema and stable VF for at least 6 months. Macular and peripapillary RNFL thickness measurements were determined. Comparisons were made using Generalized Estimated Equations. Correlations between OCT and VF measurements were also verified.Results All macular and most RNFL thickness measurements were significantly reduced in eyes with resolved papilledema from PTC syndrome compared to normal controls. Although both OCT‐measured macular and RNFL thickness measurements correlated with visual loss on SAP, correlation coefficients were greater for former.Conclusion Eyes with chronic papilledema show significant macular thinning which is correlated with the severity of VF loss. Macular thickness measurements could potentially estimate the amount of ganglion cell loss during follow‐up of patients with pseudotumor cerebri syndrome.

Low-fluence photodynamic therapy combinations in the treatment of exudative age-related macular degeneration.

To compare the efficacy of low-fluence photodynamic therapy (PDT) combinations in the treatment of age-related macular degeneration (AMD). Forty-five previously untreated eyes of 45 patients with exudative AMD whose best-corrected visual acuity (BCVA) was ≥0.3 (Snellen) were enrolled. 15 patients in Group I underwent low-fluence PDT (25J/cm(2)-300mW/cm(2)-83sec) and intravitreal pegaptanib combination, 15 patients in Group II underwent PDT (50J/cm(2)-600mW/cm(2)-83sec) and intravitreal pegaptanib combination while, 15 patients in Group III underwent intravitreal pegaptanib monotherapy. Complete ophthalmologic examinations were performed in pre and post treatment visits, and the results were statistically analised. A clinical activity score (CAS) was calculated by using changes in lesion size, amount of hemorrhage, staining pattern in FA and OCT measurement of intra/subretinal fluid. ≤ 3 logMAR lines of decrease in BCVA and decrease in CAS were considered as successful treatment. The mean age of 19 female (42.2%) and 26 male (57.8%) patients was 72.82±8.02 years. Mean follow-up was 13.93±5.87 months. Lesion type was occult in 28 eyes (62.2%). Treatment success rates according to BCVA assessments were 86.7%, 80%, 60% and mean BCVA decrease were 0.3, 1.0, 2.2 logMAR lines in Group I, II and III, respectively (P>0.05). According to the changes in central macular thickness and CAS, no difference was found among the study groups (P=0.850 and P=0.811, respectively). Patients treated with combination regimens had lower intravitreal injection frequencies (P=0.015). Combination regimen with intravitreal pegaptanib and low-fluence PDT seems to be safe and effective in stabilizing the clinical activity and BCVA in exudative AMD.

Angepasstes und standardisiertes Patientenmanagement bei der Behandlung der neovaskulären AMD im ambulanten Bereich einer Universitäts-Augenklinik

Visual results in treating neovascular age-related macular degeneration (AMD) using intravitreal injected anti-VEGF (IVT) clearly depend on injection frequency. Regarding to the European approval Ranibizumab has to be used only in cases of recurrent visual loss after the loading phase. In contrast monthly treatment--as also provided in the ANCHOR and MARINA studies--is generally allowed in Switzerland. However, it is commonly tried to reduce the injection frequency because of the particular cost situation in all health systems and of cause also due to the necessary strict monitoring and reinjection regimes, which raise management problems with increasing patient numbers. In this article the special treatment regimes of our University Eye Hospital is presented, in which a reduced injection frequency basically leads to the same increased and stable visual results as in ANCHOR and MARINA; however, needing significantly more injections as generally provided in other countries of Europe. The main focus for achieving this in a large number of patients is placed on re-structuring our outpatient flow for IVT patients with particular emphasis on patient separation and standardisation of treatment steps leading to significantly reduced time consumption per patient. Measurements of timing and patient satisfaction before and after restructuring underline its importance in order to be able to treat more patients at a high quality even in the future. The exceptional importance of spectral domain OCT measurements as the most important criterium for indicating re-treatment is illustrated.

Optic Disc Imaging with Spectral-Domain Optical Coherence Tomography: Variability and Agreement Study with Heidelberg Retinal Tomograph

To evaluate the agreement of optic disc measurements obtained with the Cirrus high-density optical coherence tomography (HD-OCT) and the Heidelberg retina tomograph (HRT) and compare the intervisit, test-retest variability between the instruments. Prospective, cross-sectional study. Two hundred seven subjects (109 glaucoma and 98 normal subjects). One eye from each individual was selected randomly for optic disc imaging by the Cirrus HD-OCT and the HRT. Areas of the optic disc and the cup, cup volume, vertical cup-to-disc ratio and cup-to-disc area ratio were compared between the instruments. The OCT measurements were corrected for ocular magnification using the Littman's formula. The measurement agreement was evaluated with the Bland-Altman plots. The intervisit test-retest variability was examined in 17 randomly selected glaucoma patients who underwent optic disc imaging weekly for 8 consecutive weeks. The intraclass correlation coefficients (ICC) and the reproducibility coefficients of the optic disc parameters were computed. Measurement agreement, reproducibility coefficients, and ICCs of optic disc parameters. The OCT measured smaller optic disc and rim areas and greater cup volume, vertical cup-to-disc ratio and cup-to-disc area ratio than the HRT did (all with P<0.001). There were proportional biases in the Bland-Altman plots between OCT and HRT optic disc measurements except for rim area and cup-to-disc area ratio. The 95% limits of agreement of rim area ranged between -0.28 and 0.88 mm(2) before, and between -0.22 and 0.92 mm(2) after correction for ocular magnification. Both OCT and HRT showed high test-retest reproducibility with ICCs ≥ 0.921. Although the reproducibility coefficient of OCT rim area (0.093 mm(2); 95% confidence interval [CI], 0.081-0.105 mm(2)) was significantly smaller than that of the HRT (0.186 mm(2); 95% CI, 0.163-0.210 mm(2); P = .018), there were no differences in the ICCs between the instruments. Optic disc assessment by spectral-domain OCT and confocal scanning laser ophthalmoscopy demonstrates poor agreement but similarly low test-retest variability. The source of their disagreement and its effects on the detection of progression require further study.

Imaging thermal expansion and retinal tissue changes during photocoagulation by high speed OCT

Visualizing retinal photocoagulation by real-time OCT measurements may considerably improve the understanding of thermally induced tissue changes and might enable a better reproducibility of the ocular laser treatment. High speed Doppler OCT with 860 frames per second imaged tissue changes in the fundus of enucleated porcine eyes during laser irradiation. Tissue motion, measured by Doppler OCT with nanometer resolution, was correlated with the temperature increase, which was measured non-invasively by optoacoustics. In enucleated eyes, the increase of the OCT signal near the retinal pigment epithelium (RPE) corresponded well to the macroscopically visible whitening of the tissue. At low irradiance, Doppler OCT revealed additionally a reversible thermal expansion of the retina. At higher irradiance additional movement due to irreversible tissue changes was observed. Measurements of the tissue expansion were also possible in vivo in a rabbit with submicrometer resolution when global tissue motion was compensated. Doppler OCT may be used for spatially resolved measurements of retinal temperature increases and thermally induced tissue changes. It can play an important role in understanding the mechanisms of photocoagulation and, eventually, lead to new strategies for retinal laser treatments.

Fourier Domain Oct Measurement of Macular, Macular Ganglion Cell Complex, and Peripapillary RNFL Thickness in Glaucomatous Chinese Eyes

To evaluate and compare the glaucoma discrimination ability of macula, macular ganglion cell complex (mGCC), and peripapillary nerve fiber layer (ppNFL) thickness in Chinese patients using Fourier-domain optical coherence tomography (FD-OCT). A total of 64 normal subjects (N), 47 glaucoma suspects (GS), and 48 glaucoma patients (G) were enrolled in the study. The thickness of mGCC, ppNFL, and total macula were measured using RTVue-100 FD-OCT (software version: 4.0.7.5; Optovue). The GCC and ONH protocols were used for obtaining images in all subjects. For each binocular subject, one eye was chosen randomly for analysis. The average thicknesses of macular, mGCC, and ppNFL in normal eyes were significantly different from those in GS or G eyes (p<0.001). The mGCC thickness correlated well with ppNFL thickness (correlation coefficients for N, GS, and G eyes are 0.397 [p=0.001], 0.822 [p<0.0001], and 0.865 [p<0.0001]). Areas under receiver operating characteristic curve of macular, mGCC, and ppNFL thickness are 0.940 (p<0.0001), 0.998 (p<0.0001), and 0.977 (p<0.0001), discriminating G from N eyes. There was no significant difference comparing the discriminating powers of NFL, GCC, and macular thickness. The mGCC measurements provide another measurement of neural loss in glaucoma, and may serve as a promising parameter for ppNFL thickness in the clinical assessment of glaucoma. For glaucomatous eyes, mGCC and ppNFL thicknesses performed better discriminating abilities compared with macular thickness.

Ganglion Cell Loss in Relation to Visual Disability in Multiple Sclerosis

We used high-resolution spectral-domain optical coherence tomography (SD-OCT) with retinal segmentation to determine how ganglion cell loss relates to history of acute optic neuritis (ON), retinal nerve fiber layer (RNFL) thinning, visual function, and vision-related quality of life (QOL) in multiple sclerosis (MS). Cross-sectional study. A convenience sample of patients with MS (n = 122; 239 eyes) and disease-free controls (n = 31; 61 eyes). Among MS eyes, 87 had a history of ON before enrollment. The SD-OCT images were captured using Macular Cube (200×200 or 512×128) and ONH Cube 200×200 protocols. Retinal layer segmentation was performed using algorithms established for glaucoma studies. Thicknesses of the ganglion cell layer/inner plexiform layer (GCL+IPL), RNFL, outer plexiform/inner nuclear layers (OPL+INL), and outer nuclear/photoreceptor layers (ONL+PRL) were measured and compared in MS versus control eyes and MS ON versus non-ON eyes. The relation between changes in macular thickness and visual disability was also examined. The OCT measurements of GCL+IPL and RNFL thickness; high contrast visual acuity (VA); low-contrast letter acuity (LCLA) at 2.5% and 1.25% contrast; on the 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) and 10-Item Neuro-Ophthalmic Supplement composite score. Macular RNFL and GCL+IPL were significantly decreased in MS versus control eyes (P<0.001 and P = 0.001) and in MS ON versus non-ON eyes (P<0.001 for both measures). Peripapillary RNFL, macular RNFL, GCL+IPL, and the combination of macular RNFL+GCL+IPL were significantly correlated with VA (P≤0.001), 2.5% LCLA (P<0.001), and 1.25% LCLA (P≤0.001). Among OCT measurements, reductions in GCL+IPL (P<0.001), macular RNFL (P = 0.006), and the combination (macular RNFL+GCL+IPL; P<0.001) were most strongly associated with lower (worse) NEI-VFQ-25 and 10-Item Supplement QOL scores; GCL+IPL thinning was significant even accounting for macular RNFL thickness (P = 0.03 for GCL+IPL, P = 0.39 for macular RNFL). We demonstrated that GCL+IPL thinning is most significantly correlated with both visual function and vision-specific QOL in MS, and may serve as a useful structural marker of disease. Our findings parallel those of magnetic resonance imaging studies that show gray matter disease is a marker of neurologic disability in MS. Proprietary or commercial disclosure may be found after the references.

Dynamic OCT measurement of corneal deformation by an air puff in normal and cross-linked corneas

A new technique is presented for the non-invasive imaging of the dynamic response of the cornea to an air puff inducing a deformation. A spectral OCT instrument combined with an air tonometer in a non-collinear configuration was used to image the corneal deformation over full corneal cross-sections, as well as to obtain high speed measurements of the temporal evolution of the corneal apex. The entire deformation process can be dynamically visualized. A quantitative analysis allows direct extraction of several deformation parameters, such as amplitude, diameter and volume of the maximum deformation, as well as duration and speed of the increasing deformation period and the recovery period. The potential of the technique is demonstrated on porcine corneas in vitro under constant IOP for several conditions (untreated, after riboflavin instillation and under cross-linking with ultraviolet light), as well as on human corneas in vivo. The new technique has proved very sensitive to detect differences in the deformation parameters across conditions. We have confirmed non-invasively that Riboflavin and UV-cross-linking induce changes in the corneal biomechanical properties. Those differences appear to be the result of changes in constituent properties of the cornea, and not a consequence of changes in corneal thickness, geometry or IOP. These measurements are a first step for the estimation of the biomechanical properties of corneal tissue, at an individual level and in vivo, to improve diagnosis and prognosis of diseases and treatments involving changes in the biomechanical properties of the cornea.

Optical coherence tomography for guidance of treatment of in-stent restenosis with cutting balloons

The treatment of in-stent restenosis (ISR) remains a challenge with poor immediate results and higher restenosis rate than in de novo lesions. We propose, based on a consecutive series of patients treated with cutting balloon, a strategy of aggressive device selection based on the results of serial FD-OCT assessment. Fourteen consecutive ISR lesions were evaluated both angiographically and with frequency domain optical coherence tomography (FD-OCT) (C7; LightLab Imaging Inc., Westford, MA, USA). Cutting balloon (CB) was used in all cases, sized firstly according to conventional angiographic criteria and then upgraded based on OCT assessment with the aim of creating cuts as close as possible to the struts. OCT data analysis included measurements of lumen and stent area, minimal distance lumen-struts and residual plaque neointimal hyperplasia. With an OCT guided CB strategy, the final minimal lumen cross-sectional area (MLCSA) after the final treatment reached 6.68±1.14 mm², with a reduction from 69% to 25% of neointimal hyperplasia. In the patients with a two-step strategy using a first CB guided by angiography and a second CB guided by OCT, the increase in CB diameter was 0.5 mm, achieving an increase in MLCSA area from 4.9±0.42 to 6.35±0.92 mm² with a reduction from 41% to 27% of neointimal hyperplasia. The OCT measurements of strut-to-strut distance allow safe upsizing of the CB with an acceptable lumen increase before deployment of a new DES. The strategy appears of particular usefulness for a DEB strategy with no intention to implant new stents.

Evaluation of the Nerve Fiber Layer and Macula in the Eyes of Healthy Children Using Spectral-Domain Optical Coherence Tomography

To determine the normative values of the peripapillary retinal nerve fiber layer (RNFL), macular thickness, and macular volume in healthy children using spectral-domain optical coherence tomography (SD-OCT) and analyze the correlation of such values with age, refraction error, and biometric measurements. Observational case series. This institutional study involved 107 eyes from 107 healthy pediatric patients (54 female, 53 male) with ages between 6 and 16 years. After the biometric measurements and refractive error values (in spherical equivalent) of the cases were obtained, the peripapillary RNFL, macular thickness, and macular volume values were calculated using the Spectralis OCT device. Among the study group, with an average age of 10.46 ± 2.94 years, the average axial length (AL) was 23.33 ± 0.89 mm; the average spherical equivalent (SE) value was -0.27 ± 0.99 diopter. The average peripapillary RNFL thickness was 106.45 ± 9.41 μm; the average macular thickness was 326.44 ± 14.17 μm; and the average macular volume was 0.257 ± 0.011 mm(3). The aforementioned OCT measurements were not significantly correlated with age, SE, or AL values (P > .05 for all). This study reports SD-OCT findings among healthy pediatric cases. SD-OCT can be reliably used for pediatric patients because of its short exposure time and high degree of image resolution.