Influence of cataract surgery on repeatability and measurements of spectral domain optical coherence tomography.

BACKGROUNDS/AIMS: To evaluate the effect of uncomplicated cataract phacoemulsification on the measurements of macular and retinal nerve fibre layer (RNFL) in healthy subjects using two spectral domain (SD) optical coherence tomography (OCT) instruments--Cirrus OCT (Zeiss) and Spectralis OCT (Heidelberg)--and to assess the reliability of the measurements obtained with these two devices before and after cataract surgery. METHODS: The study included 60 eyes of 60 healthy subjects (22 men and 38 women, 54-88 years of age) who underwent cataract phacoemulsification. One month before and one month after surgery, three repetitions of scans were performed using the RNFL and macular analysis protocols of the Cirrus and Spectralis OCT instruments. The differences between RNFL and macular thickness measurements obtained in the two visits were analysed. Repeatability was evaluated by calculating the coefficient of variation (COV) for each of the parameters recorded and for each visit. RESULTS: The RNFL measurements obtained with the Cirrus and Spectralis OCT differed before and after surgery, and most of these differences were statistically significant (p<0.05). Macular thickness measurements using the Spectralis OCT were not significantly different between the two visits, whereas the differences found with the Cirrus OCT were statistically significant. The repeatability was better after surgical removal of the cataract, and the differences between COV in the two visits were significant with the Cirrus OCT. CONCLUSIONS: The presence of cataracts affects RNFL and macular measurements performed with SD-OCT. The repeatability of the images significantly improved after cataract phacoemulsification when using the Cirrus OCT.

Optical coherence tomography in retinitis pigmentosa: reproducibility and capacity to detect macular and retinal nerve fiber layer thickness alterations.

PURPOSE: To evaluate the ability of time-domain and Fourier-domain optical coherence tomographies (OCTs) to detect macular and retinal nerve fiber layer atrophies in retinitis pigmentosa (RP). To test the intrasession reproducibility using three OCT instruments (Stratus, Cirrus, and Spectralis). METHODS: Eighty eyes of 80 subjects (40 RP patients and 40 healthy subjects) underwent a visual field examination, together with 3 macular scans and 3 optic disk evaluations by the same experienced examiner using 3 OCT instruments. Differences between healthy and RP eyes were compared. The relationship between measurements with each OCT instrument was evaluated. Repeatability was studied by intraclass correlation coefficients and coefficients of variation. RESULTS: Macular and retinal nerve fiber layer atrophies were detected in RP patients for all OCT parameters. Macular and retinal nerve fiber layer thicknesses, as determined by the different OCTs, were correlated but significantly different (P < 0.05). Reproducibility was moderately high using Stratus, good using Cirrus and Spectralis, and excellent using the Tru-track technology of Spectralis. In RP eyes, measurements showed higher variability compared with healthy eyes. CONCLUSION: Differences in thickness measurements existed between OCT instruments, despite there being a high degree of correlation. Fourier-domain OCT can be considered a valid and repeatability technique to detect retinal nerve fiber layer atrophy in RP patients.

Comparison of retinal nerve fiber layer thickness measurements in healthy subjects using fourier and time domain optical coherence tomography.

Purpose. To compare the retinal nerve fiber layer (RNFL) measurements using two different ocular coherence tomography (OCT) devices: Cirrus Fourier domain OCT and Stratus time domain OCT. To analyze reproducibility of Fourier domain measurements in healthy subjects. Methods. One hundred and thirty-two eyes of 132 healthy subjects were scaned on the same day with both instruments, separated by 10 minutes from each other. Thickness of quadrant, average and the 12 different areas around the optic nerve were compared between Cirrus and Stratus. Repeatability, intraclass correlation coefficients (ICCs), and coefficients of variation (COVs) were calculated in RNFL measurements provided by Fourier domain device. Results. The average thickness in the optic cube was 95.50 µm using Cirrus and 97.85 µm using Stratus. Average thickness and temporal quadrant showed significant differences using Cirrus and Stratus methods. Reproducibility was better with Fourier domain OCT (mean COV of 4.54%) than with Stratus time-domain OCT (mean COV of 5.57%). Conclusions. Both scan options give reproducible RNFL thickness measurement, but there are differences between them. Measurements obtained using Fourier domain device show better reproducibility.

Risk factors for progressive axonal degeneration of the retinal nerve fibre layer in multiple sclerosis patients.

AIM: To quantify structural and functional degeneration in the retinal nerve fibre layer (RNFL) of patients with multiple sclerosis (MS) over a 2-year time period, and to analyse the effect of prior optic neuritis (ON) as well as the duration and incidence of MS relapses. METHODS: 166 MS patients and 120 healthy controls underwent assessment of visual acuity and colour vision, visual field examination, optical coherence tomography, scanning laser polarimetry and visual evoked potentials (VEPs). All subjects were re-evaluated after a period of 12 and 24 months. RESULTS: Changes in the optic nerve were detected by structural measurements but not by functional assessments. Changes registered in MS patients were greater than changes in healthy controls (p<0.05). Eyes with previous ON showed a greater reduction of parameters in the baseline evaluation, but RNFL atrophy was not significantly greater in the longitudinal study. Patients with MS relapses showed a greater reduction of RNFL thickness and VEP amplitude compared with non-relapsing cases. Patients with and without treatment showed similar measurement reduction, but the non-treated group had a significantly higher increase in Expanded Disability Status Scale (p=0.029). CONCLUSIONS: MS causes progressive axonal loss in the optic nerve, regardless of a history of ON. This ganglion cell atrophy occurs in all eyes but is more marked in MS eyes than in healthy eyes.

Is there a prognostic role of K-ras point mutations in the serum of patients with advanced non-small cell lung cancer?

The purpose of this study was to investigate the prognostic significance of K-ras mutations in circulating DNA in advanced non-small lung cancer (NSCLC) patients. Serum samples were assessed prior to platinum-based chemotherapy start in 67 patients with advanced NSCLC (stage IIIB or IV), treated between April 1999 and June 2002. Patients were not previously treated with chemotherapy. K-ras oncogene mutations at codon 12 were analyzed by genomic amplification and direct sequencing of the patient's DNA present in serum. Pre-treatment serum was available in all 67 patients. Twenty patients (30%) demonstrated K-ras mutations while 47 patients (70%) had wild-type K-ras. Among K-ras mutations, the amino acid glycine was substituted by cystein in 90% and valine in 10%. When patients were grouped according to K-ras genotype, there was no significant difference for any of the baseline patient characteristics. There was a tendency towards a higher response rate for patients with K-ras mutations versus wild-type K-ras in serum, however not statistically significant (p=0.37). Median progression-free survival was 7.3 months versus 5.5 months in patients with mutations and with wild-type K-ras, respectively (p=0.23). For median overall survival time, the mutation group was comparable to the wild-type K-ras group with 12.5 and 11.4 months, respectively (p=0.28). In conclusion, there were no significant differences between the patients with K-ras mutations and those with wild-type genotype with respect to baseline patient characteristics, response rates, progression-free survival, or overall survival.

Assessment of nucleotide excision repair XPD polymorphisms in the peripheral blood of gemcitabine/cisplatin-treated advanced non-small-cell lung cancer patients.

Only about one third of non-small-cell lung cancer (NSCLC) patients respond to cisplatin-based chemotherapy. Cisplatin DNA adducts are commonly repaired through the nucleotide excision repair pathway. The study of rare inherited disorders such as xeroderma pigmentosum and Cockayne syndrome has disclosed that XP genes, including XPD, play an essential role in DNA repair, both in the global genomic repair and in the transcription-coupled repair pathways. XPD polymorphism and decreased expression of XP genes have both been linked to lower DNA repair capacity. ERCC1 overexpression has been associated with cisplatin resistance, and experimental evidence shows a close association between ERCC1 and XPD. In the present study, we have examined XPD polymorphisms at codons 751 and 312 in DNA isolated from peripheral blood in 39 patients with gemcitabine/cisplatin-treated locally advanced non-small-cell lung cancer Although no significant correlation was observed between XPD genotype and objective response, a trend toward better response was observed in patients with XPD polymorphism at codon 312. The map of the nucleotide excision repair pathway can be used to design translational research studies to identify and validate predictive markers of response to cisplatin, and the Spanish Lung Cancer Group has recently accrued 250 gemcitabine/cisplatin-treated NSCLC patients for a prospective assessment of XPD genotype