Clinical characteristics of patients in contact lens clinic, Siriraj Hospital.

Objective: To study the clinical characteristics of patients attending the contact lens clinic at Siriraj Hospital. Methods: Retrospective chart indicates characteristics of new patients who attended the contact lens clinic at Siriraj Hospital from January 2008 to December 2009. Results: One hundred and thirty three eyes were collected from 85 patients (50 females and 35 males) with the mean age of 31.87 years: 40 eyes were low refractive error, 23 eyes were high myopia, 22 eyes were high hyperopia, 18 eyes were high astigmatism, 18 eyes were high myopia and high astigmatism and 12 eyes were keratoconus. The mean pre-fitting visual acuity in all groups was 0.79LogMAR (range 0 to 2.6LogMAR). Soft sphere contact lenses were mostly prescribed in low refractive error patients while PMMA contact lenses were mostly prescribed in keratoconus patients. The mean final visual acuity with contact lenses in all groups was 0.2LogMAR (range 0 to 1LogMAR). No serious contact lens related complications were found in the follow up visit. Conclusion: Many types of contact lenses can be used in different indications. Contact lenses can improve visual acuity substantially in high hyperopia patients. To wear contact lenses is a less invasive option for moderate keratoconus patients to improve vision. Patient’s education for contact lens caring is important and should be emphasized to prevent irreversible contact lens related complications.

Normative data of electroretinogram and visual evoked potential in Thai population.

Objective : To define normal values of Electroretinogram [ERG] and Visual Evoked Potential [VEP] in different age groups using Viking Select Master Software V7.1. Methods: ERG and VEP values were measured using Viking Select Master Software V7.1 in selected subjects without history of ocular and/or systemic diseases that affect ERG and VEP values. Results were studied in three groups of age: less than 10 years old, 11 to 40 years old and over 40 years old. Results: There were 26 eyes in the first group with age range from 6-10 years old [mean 7.8 + 1.52 years old]. In ERG : the normal values of photopic amplitude of ; a-wave was> 18.57 microvoltage [ตV] and b-wave was> 23.82 ตV, flickering amplitude of b-wave was > 21.93 ตV, scotopic amplitude of b-wave was> 39.12 ตV, mesopic amplitude of ; a-wave was > 60.44 ตV and b-wave was > 96.84 ตV. In VEP : transient flash amplitude was> 20.58 ตV and latency was < 94.10 millisecond[ms], transient pattern size 2 amplitude was > 8.61 ตV and latency was < 100.00 ms. There were 75 eyes in the second group with age range from 11-38 years old [mean 26.8 + 7.35 years old]. The values of photopic amplitude of ; a-wave was > 22.56 ตV and b-wave was > 20.14 ตV, flickering amplitude of b-wave was > 19.35 ตV, scotopic amplitude of b-wave was > 32.29 ตV, mesopic amplitude of ; a-wave was > 45.05 ตV and b-wave was> 78.97 ตV, VEP- transient flash amplitude was > 11.64 ตV and latency was < 96.78 ms, transient pattern size 2 amplitude was > 4.82 ตV and latency was < 88.49 ms. There were 77 eyes in the third group with age range from 41-81 years old [mean 60.1 + 11.54 years old]. The values of photopic amplitude of; a-wave was > 19.12 ตV and b-wave was > 24.59 ตV, flickering amplitude of b-wave was > 18.76 ตV, scotopic amplitude of b-wave was > 35.60 ตV, mesopic amplitude of ; a-wave was > 40.90 ตV and b-wave was > 94.09 ตV, VEP- transient flash amplitude was > 10.07 ตV and latency was < 102.10 ms, transient pattern size 2 amplitude was > 5.34 ตV and latency was < 96.00 ms. Conclusion: We established normal ERG and VEP values in different age group using Viking Select Master Software V7.1 at Siriraj Hospital to distinguish between normal and pathological patients. The values are affected in relation to machine and environmental setting in different laboratory. It is essential for individual laboratories to set their own normal values.