1,721,037 research outputs found
Imaging and diagnostic capabilities of anterior segment optical coherence tomography in microbial keratitis
No full textPurpose: Anterior segment optical coherence tomography (AS-OCT) provides high-resolution non-contact corneal scans. We have investigated the imaging and diagnostic capabilities of AS-OCT in microbial keratitis. Primary aim was to assess the ability of AS-OCT to measure corneal thickness in the area affected by microbial keratitis. Secondary aim was to assess AS-OCT qualitative and quantitative parameters during the course of the disease.Method: A prospective study of 10 patients (eyes) with culture proven microbial keratitis. Patients underwent standard clinical examination and treatment based on slit-lamp findings. AS-OCT scanning was performed on presentation, 2–4 days, 6–8 days, and14 days or longer on treatment. In all scans the scanning beam passed through the centre of the infiltration at a specific meridian. All scans were performed by one investigator.Results: Corneal thickness in the infiltrated region could be measured in nine eyes; in one eye the endothelial surface was indistinguishable from an endothelial inflammatory mass. Eight of these nine eyes responded well to topical antibiotic treatment, one required penetrating keratoplasty. In all 8 cases, clinical improvement was associated with reduction in corneal thickness on serial scanning. Mean corneal thickness on presentation was 939 mm (SD 89), decreasing to 797mm (SD 80) (p = 0.08), 703 mm (SD 60) (p < 0.05) and 640 mm(SD 64) (p < 0.05) at the above intervals. In the eye that required surgery, clinical deterioration correlated with AS-OCT corneal thinning progression and descmetocoele formation. Other parameters that could be measured included infiltration depth and dimensions of endothelial inflammatory mass. AS-OCT provided a range of qualitative parameters. Corneal infiltration was imaged as a hyper-reflective area in the corneal stroma. Anterior chamber inflammatory cells and retrocorneal pathology could also be imaged.Conclusion: AS-OCT imaging provides a range of parameters that can be used to objectively assess microbial keratitis. Serial scans can aid objective evaluation of response to treatment
In-vivo study of human microbial keratitis with anterior segment OCT
No full textPurpose: : Anterior Segment Optical Coherence Tomography (AS-OCT) is a novel imaging modality that provides high-resolution corneal scans by non-contact examination. We investigate microbial keratitis (MK) in a prospective longitudinal study with AS-OCT. We assess the ability of Visante AS-OCT to measure corneal thickness (CT) and infiltrate thickness (IT) in the affected area and investigate the temporal change of these parameters during the course of the disease.Methods: : Twenty seven patients with suspected microbial keratitis underwent slit-lamp examination and AS-OCT scans on day of presentation and days 3, 7 and 14 post-presentation. The scanning beam passed through the infiltrate centre at a specific meridian for all scans. Measurements of CT and IT were obtained in the centre of the infiltrated area on high-resolution images with calliper tools provided by the Visante OCT software (version 1.1.2). Scans and measurements were carried out by the same investigator.Results: : Clinical resolution occurred in 26 cases; mean CT decreased from 898m (SD±204) on presentation to 753m (SD±161) [p<0.01], 677m (SD±178) [p<0.001] and 584m (SD±146) [p<0.001] on days 3, 7 and 14 respectively. Mean IT decreased from 394m (SD±182) to 319m (SD±162) [p=0.16], 295m (SD±135) [p=0.06] and 207m (SD±87) [p<0.001] respectively. CT and IT decreased significantly more rapidly (48m/day and 25m/day respectively) in the first 3 days of treatment compared to later time intervals, 3-7 and 7-14 days (p<0.05). In one case with clinical deterioration, CT decreased and IT increased before penetrating keratoplasty was required for perforation.Conclusions: : This is the first study to measure in-vivo CT and IT during the clinical course of MK. Clinical resolution is associated with a rapid reduction of CT and IT the first 3 days of treatment; CT decreases significantly by day 3, whereas IT only decreases significantly by day 14. AS-OCT provides serial objective assessment of the extent and depth of corneal inflammation
Recent advances in ophthalmic anterior segment imaging: a new era for ophthalmic diagnosis?
No full textAnterior segment imaging is a rapidly advancing field of ophthalmology. New imaging modalities, such as rotating Scheimpflug imaging (Pentacam-Scheimpflug) and anterior segment optical coherence tomography (Visante OCT and Slit-Lamp OCT), have recently become commercially available. These new modalities supplement the more established imaging devices of Orbscan scanning slit topography and ultrasound biomicroscopy (UBM). All devices promise quantitative information and qualitative imaging of the cornea and anterior chamber. They provide a quantitative angle estimation by calculating the angle between the iris surface and the posterior corneal surface. Direct angle visualisation is possible with the OCT devices and UBM; they provide images of the scleral spur, ciliary body, ciliary sulcus and even canal of Schlemm in some eyes. Pentacam-Scheimpflug can measure net corneal power, a feature particularly useful for cataract patients having undergone previous corneal surgery. Anterior segment OCT can measure corneal flap depth following LASIK and anterior chamber width prior to phakic intraocular lens implantation. The arrival of the new imaging devices may herald the dawn of a new era for ophthalmic diagnosis, particularly in view of the ease and non-contact nature of examination
Keratometric analysis of thin and ultrathin DSEK
No full textPurpose: : Descemet stripping endothelial keratoplasty has been established as the treatment ofchoice in endothelial dysfunction. There remains a major controversy whether the difference between thinner and thicker grafts has a significant impact on visual outcome. Ouraim is to evaluate the influence of ultrathin and thin DSEK grafts on the optical performanceof the cornea post DSEK and determine whether there is a difference in the optical performance between thin and ultrathin graft lenticules
Methods: : We studied two groups of patients one with regular donor thickness ( thin grafts131 µm or more) and one with ultrathin grafts (130 µm or less). All DSEK patients were assessed by means Pentacam HR rotating slit beam Scheimpflug imaging (Oculus, Wetzlar, Germany) and best corrected visual acuity (BCVA). Graft thickness post-operatively was measured by Visante OCT. 34 eyes of 32 patients were included in the keratometric evaluation.
Results: : Mean age of the patients was 72yr (range 36-90), Median 75yr. Minimum F/U- 4m - Mean 13.3 (range 4-22), Median 11.5m. Oculus Pentacam HR >130 μm LOA mean ± SD 0.67 ± 0.37 Range 0.34 -1.52 HOA mean ± SD 0.13 ± 0.06 Range 0.07 -0.26 TA mean± SD 0.67 ± 0.37 Range 0.31 - 1.54 Oculus Pentacam HR <130 μm LOA mean ± SD 0.60 ± 0.15 Range 0.38 - 0.99 HOA mean ± SD 0.141± 0.03 Range 0.09 - 0.16 TA mean ± SD 0.64 ± 0.15 Range 0.37 - 1.00Low order, high order and total aberrations measured at 8mm did not correlate with graft or corneal thickness.
Conclusions: : No significant difference was found when BCVA was compared between ultrathingrafts (<130μm) and grafts >130μm. Only patients with ultrathin grafts achievedBCVA of 0.2 or better. No significant correlation existed between donor lenticule, host corneal and total corneal thickness with BCVA and corneal aberrations. No significant difference was found in low and high\ order aberrations of the two groups but the total aberrations were significantly different between the ultrathin and the thin DSEK group
Indications for emergency corneal grafting 1999-2005: Preliminary analysis of the United Kingdom corneal transplant register
No full textPurpose:: To identify and quantify the indications for emergency corneal grafting (eCG) in the United Kingdom (UK) and the Republic of Ireland (ROI) over a period from 1999 to 2005.Methods:: Prospective, multifactorial analyses of all corneal grafts registered by the United Kingdom Transplant Service from April 1999 to March 2005. eCGs were classified by using ‘reasons for grafts’: therapeutic grafts (severe infection, threatened or actual perforation), as selected by corneal transplant surgeons on the United Kingdom Transplant Registration Form. Of these cases the underlying diagnostic condition was analysed.Results:: In the study period a total of 12976 corneal grafts were performed of which 11646 (88.6%) were done under routine conditions and 1330 (11.4%) under emergency circumstances (including 433 regrafts). The main reason for an eCG was actual perforation in 876 (65.9%) patients. The main diagnostic categories for eCG were infection (353 patients, 39.4%) and ulcerative keratitis (289 patients, 32.2%). Other conditions such as ectasias (7%), previous ocular surgery (5.7%), ocular injury (4.1%), dystrophies (2.6%) and opacification (1.9%) were less frequent.Conclusions:: The data in this study shows the largest cohort of emegency corneal grafts ever to be reported. Our findings show that a significant percentage of corneal grafting in the UK & ROI is performed under emergency conditions. Typically, the most frequent indication for eCG is treatment of a corneal perforation following infection
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