Arterial pulsatility as an index of cerebral microangiopathy in diabetes type 2.

Transcranial doppler is an inexpensive, non-invasive investigation. This study assessed its validity in determining cerebral small vessel disease in patients with type 2 diabetes mellitus. Flow velocity and pulsatility index were measured in the middle cerebral, basilar and intracranial internal carotid arteries of a sample of 141 diabetic patients with no other risk factors, and 132 age- and sex-matched healthy controls. The patients were divided into 2 groups: 73 with complicated and 68 with uncomplicated diabetes. There was a statistically significant difference between the complicated diabetes and control groups for the 3 arteries and most indices. The differences between the uncomplicated diabetes patients and the controls were also statistically significant but less strongly. Transcranial doppler may be useful in early diagnosis of cerebral small vessel disease in patients with type 2 diabetes mellitus.

Tear IgA and serum IgG antibodies against Acanthamoeba in patients with Acanthamoeba keratitis.

PURPOSE: Exposure to Acanthamoebaspecies appears to be ubiquitous, as 50% to 100% of healthy human subjects display anti-Acanthamoebaantibodies. However, the presence of specific anti-Acanthamoebaantibodies in the serum and tears of patients has not been investigated. The prevalence of serum immunoglobulin G (IgG) and tear IgA against three species of Acanthamoebawas assessed in healthy subjects and patients with Acanthamoebakeratitis. METHODS: The level of specific serum IgG and tear IgA against A. castellanii, A. astronyxis, and A. culbertsoniin the sera of 23 patients and 25 healthy subjects was tested by enzyme-linked immunosorbent assays. Total serum IgM, IgG, and IgA concentrations were measured by nephelometry. Acanthamoebakeratitis was diagnosed clinically and confirmed by in vivo confocal microscopy. In some patients, corneal biopsies were also performed and trophozoites were cultured on lawns of Escherichia colion non-nutrient agar. RESULTS: All healthy subjects and patients with Acanthamoebakeratitis had detectable serum IgG antibodies against all Acanthamoebaantigens. However, patients with Acanthamoebakeratitis had significantly higher anti-AcanthamoebaIgG antibody titers than healthy subjects. In contrast, Acanthamoeba-specific tear IgA was significantly lower in patients with Acanthamoebakeratitis in comparison with healthy subjects. Total serum immunoglobulins did not differ significantly between healthy subjects and patients with Acanthamoebakeratitis. CONCLUSIONS: The results suggest that a low level of anti-AcanthamoebaIgA antibody in the tears appears to be associated with Acanthamoebakeratitis.

Specular microscopy, confocal microscopy, and ultrasound biomicroscopy: diagnostic tools of the past quarter century.

PURPOSE: To identify, characterize, and illustrate the most important past and future potential contributions of specular, confocal, and ultrasound biomicroscopy to clinical diagnosis and research applications in the cornea from the past 25 years. METHODS: Specular microscopy, in vivo tandem scanning confocal microscopy (TSCM), scanning slit confocal microscopy (SSCM), and high-frequency ultrasound biomicroscopy are examined. RESULTS AND CONCLUSIONS: This review demonstrates the abilities and limitations of three powerful new in vivo imaging modalities to resolve the cellular and structural layers of the cornea temporally and spatially in three or four dimensions, (x, y, z, t). Clinical pathological processes such as inflammation. infection, wound healing, toxicity, embryonic development, differentiation, and disease, which previously could be studied only under static ex vivo conditions, can now be dynamically evaluated over time. Thus, with continued development and application in vivo, noninvasive microscopic techniques should provide exciting new insights into understanding the structure and function of not only the eye, but also other multicellular organ systems in health and disease. These new imaging paradigms are in the first rank of advances in medical science in the past quarter century.

Excimer laser treatment of spherical hyperopia: PRK or LASIK?

PURPOSE: To compare the efficacy and safety of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) in the treatment of spherical hyperopia with use of the VISX STAR S2 excimer laser. METHODS: A review of 15 consecutive patients (22 eyes) receiving PRK and 22 consecutive patients (26 eyes) receiving LASIK (median follow-up, 12 months). RESULTS: Mean age was 52 +/- 7 years for patients receiving PRK and 55 +/- 9 years for patients receiving LASIK. Mean preoperative spherical equivalent was +2.25 +/- 1.16 D for PRK patients and +1.81 +/- 0.92 D for LASIK patients. Mean deviation from intended correction was -0.82 +/- 0.89 D after PRK and +0.19 +/- 0.47 D after LASIK at 1 month (P < .01); +0.16 D +/- 0.37 D after PRK and +0.29 +/- 0.51 D after LASIK at 6 months (P = .906); +0.20 +/- 0.35 D after PRK and +0.37 +/- 0.44 D after LASIK at 1 year (P = .301). At 1 year, 83.3% of PRK eyes and 61.5% of hyperopic LASIK eyes were within +/- 0.50 D of intended correction (P = 1.0). At 1 year, all eyes in both groups had acuity of 20/40 or better uncorrected, and 47.1% of PRK eyes and 54.5% of LASIK eyes had acuity of 20/20 or better uncorrected (P = 1.0). At last follow-up (minimum, 6 months), 2 eyes in each group had lost 2 lines of best spectacle-correct visual acuity, but none had lost more than 2 lines. All PRK patients experienced significant postoperative pain that required systemic medication. LASIK patients had only minor, transient discomfort. CONCLUSION: LASIK and PRK are of comparable efficacy and safety. However, PRK was associated with significant post-operative pain, an initial and temporary myopic overshoot peaking at 1 month, and stability not occurring before 6 months. LASIK was less painful and was associated with more rapid stability (at 1 month) and a trend toward better uncorrected visual acuity, although not statistically significant.

Subretinal microsurgery with gradient index endoscopes.

State-of-the-art subretinal surgery involves a standard three-port pars plana entry, followed by an iatrogenic retinotomy to access the subretinal space. Subretinal manipulations through a small retinotomy are made possible by specially designed instruments. As the surgeon looks through the vitreous cavity, all subretinal maneuvers are obscured by the overlying retina. Consequently, the surgeon is operating 'blindly' and has to rely on 'feeling' rather than direct visualization. Micro-endoscopic viewing systems are the ideal solution for visualization during subretinal surgery. Until now, such endoscopes were either too large for intraocular use or lacked sufficient resolution, especially at a short working distance. Recently, a gradient index (GRIN) endoscope was developed (Insight Instruments, Inc., Lake Mary, Fla., USA) combining a small diameter (0.89 mm, 20 gauge) and incorporating excellent optical resolution, even at extremely close working distances. After ballooning a limited part of the retina without creating a retinal hole, the 20-gauge GRIN endoscope can be introduced into the subretinal space through the sclera and choroid, posterior to the pars plana. Surgical instruments can then be introduced into the subretinal space through a second neighboring sclerotomy. Thus, subretinal surgery can be performed under direct endoscopic control. As a result of direct visualization, the surgeon may perform certain surgical procedures with greater accuracy, i.e., subretinal neovascular membranes may be dissected meticulously from the neurosensory retina and retinal pigment epithelium, minimizing damage to both structures. The feeding choroidal vessel can be identified and directly coagulated, which is usually very difficult during conventional subretinal surgery. Endoscopic subretinal surgery is thus a significant improvement over conventional methods, avoiding the need for a retinotomy and increasing the safety and facility of the surgery itself.