Diagnostic value of visual evoked potentials for clinical diagnosis of multiple sclerosis.

PURPOSE: Prolonged latency of visual evoked potentials (VEP) has been used to identify clinically silent lesions in multiple sclerosis (MS) suspects. The objective of this study was to determine the reliability of VEP to predict the development of MS in MS suspects. METHODS: Retrospective hospital records of MS suspects were evaluated. VEP was analyzed together with subsequent diagnostic confirmation of MS by McDonald diagnostic criteria for MS-2005. RESULTS: MS developed in 12 of 35 patients (34 %) and 23 (66 %) failed to exhibit diagnostic characteristics. P100 latencies and interocular latency differences were longer in clinically definite multiple sclerosis (CDMS) than non-CDMS patients (p = 0.002, 0.001, respectively). All patients in the subsequent MS group had P100 latencies longer than102 ms, a mean of our MS-free subjects thus providing 100 % of sensitivity. No patient developed MS with a P100 latency <102 ms. Brain MRI lesions associated significantly with developing CDMS (p = 0.001). Predictability of developing CDMS was highest when criteria for P100 latency, interocular latency difference, and brain MRI lesions were combined. CONCLUSION: MS suspects with a P100 latency longer than mean of MS-free subjects are more likely to develop MS than those with lower values. VEP latency combined with MRI could improve the accuracy of MS prediction.

The rate of change in retinal vessel width and tortuosity in eyes at risk for retinopathy of prematurity.

PURPOSE: To describe the rate of change in retinal vessel width and tortuosity in eyes that develop treatment-requiring, or type 1, retinopathy of prematurity (ROP) versus eyes that do not develop type 1 ROP. METHODS: Posterior poles of eyes of 41 infants at risk for ROP were imaged longitudinally with a 30° fundus camera. Retinal vessel width and tortuosity were measured with computer-assisted image analysis. The rate of change per day in width and tortuosity up to the development of most severe ROP was calculated from linear regression and eyes with (n = 10) and without type 1 ROP (n = 31) were compared. RESULTS: Eyes that developed type 1 ROP had a greater rate of change in width for venules and 3 widest vessels (P < 0.0001), and a greater rate of change in tortuosity for arterioles and 3 most tortuous vessels (P < 0.0001) than eyes that did not develop type 1 ROP. These vessel parameters discriminate the 2 groups well (area under the ROC curve, 0.79-0.90). A combination of venular width and arteriolar tortuosity had the best discriminative ability (area under the ROC curve, 0.96). CONCLUSIONS: In this pilot study, eyes that eventually developed type 1 ROP demonstrated a faster increase in width and tortuosity of retinal vessels compared with those that did not. Further study of the kinetics of retinal vascular change in a larger sample may allow for the earlier identification of vision-threatening ROP.

Visual prognostic value of ocular electrophysiology tests in corneal transplantation.

OBJECTIVE: To determine visual prognostic value of electrophysiologic tests in unilateral-eye-disease patients who underwent corneal transplantation. MATERIAL AND METHOD: Retrospective charts of the patients who underwent unilateral optical penetrating keratoplasty at Siriraj Hospital from September 2003-June 2009 were reviewed. The amplitude of a-wave and b-wave in dark-adapted bright flash ERG and the amplitude of major positivity (P2) in flash VEP were recorded and compared with the good fellow eye. Area under receiver operating characteristic curve (AUC) was used to determine the best predictor of good visual prognosis. Positive predictive value (PPV) and negative predictive value (NPV) were used to determine the accuracy of the tests. RESULTS: Thirty-nine patients were included. The present study showed that a-wave amplitude was a good predictor (AUC = 0.83). For a-wave amplitude that was equal to or more than 80% and P2 amplitude that was equal to or more than 67%, PPV was 95.65%. CONCLUSION: The a-wave amplitude and P2 amplitude predict good visual outcome most accurately when changing less than 20% and 33%, respectively, compared to the normal fellow eye.

Achromatopsia: the first case report in Thailand.

Achromatopsia, also known as rod mon-ochromacy, is a congenital and nonprogressive ocular disorder characterized by an absence of functional cone photoreceptors in the retina. Affected subjects usually present in infancy with photophobia, nystagmus, low visual acuity and inability to discriminate colors. Fundus examination is normal, but electroretinography demonstrates absent photopic (cone) responses and normal scotopic (rod) responses. Achromatopsia is rare in the general population and inherited as an autosomal recessive trait. The authors report the first case of achromatopsia in Thailand with complete electrophysiological findings and long-term follow-up (8 years).

Horizontal mattress technique for superior oblique suture spacer.

Superior oblique tendon overaction and Brown syndrome have been managed surgically by means of tenotomy/tenectomy, use of a silicon expander, and elongation with autologous fascia lata. These solutions are problematic with respect to corrective precision, injury and complications, or surgical difficulty. We present a simple "mattress" suture spacer technique that allows a precise and secure intraoperative adjustment.

Tonometry after laser in situ keratomileusis treatment: a preliminary study in Thai patients.

OBJECTIVE: To evaluate the change in intraocular pressure (IOP) measurement by Goldmann applanation tonometer after Laser in Situ Keratomileusis (LASIK) for myopia and myopic astigmatism, and to assess the correlation between the changes of lOP reading and the reduction of central corneal thickness (CCT) after LASIK in Thai patients. STUDY DESIGN: Prospective correlational study. MATERIAL AND METHOD: LASIK was performed on 65 eyes of 33 patients for correction of myopia and myopic astigmatism. IOP was measured by Goldmann applanation tonometer before and 3 months after LASIK. The correlation between the change in IOP reading and the change in central corneal thickness were evaluated. RESULTS: IOP reading was significantly reduced by mean of 2.9 +/- 2.5 mmHg (p = 0.0001). The authors used Pearson analysis to study the correlation between the change in IOP and the reduction of CCT. In subgroup analysis the patients were divided by degree of myopia: group 1, myopia less than -3 diopters (D) (n = 14); group 2, myopia -3 to -6 D (n = 31); group 3, myopia greater than -6 D (n = 20)). The result showed more correlation in higher myopia group (Pearson; r = 0.158 in group 3, r = -0.098 in group 2 and r = -0.102 in group 1). CONCLUSION: Goldmann applanation tonometry underestimates the IOP in thin cornea. Variability in CCT is a potent confounder of this tonometry technique. Therefore, it has important implications for considering CCT measurement incorporated with Goldmann applanation tonometry for glaucoma diagnosis especially in myopic patients who undergo LASIK surgery.