Randomised controlled trial on the effectiveness of lidocaine gel vs tetracaine drops as the sole topical anaesthetic agent for primary pterygium surgery.

PURPOSE: To determine the effectiveness of lidocaine 2% gel vstetracaine 1% drops in primary pterygium surgery. METHODS: This was a prospective, randomised controlled trial. Forty consecutive patients who had primary pterygium underwent surgical excision of primary pterygium and mitomycin C. Patients were randomised into two groups. Group 1 received tetracaine 1% drops and solcoseryl eye gel (Solco Basel AG, Switzerland). Group 2 received xylocaine 2% gel (lidocaine hydrochloride 2% gel, AstraZeneca, Sweden) topically and normal saline drops 0.9%. Additional tetracaine drops were given to patients who experienced pain preoperatively. The primary outcome was the pain experienced during and after surgery. Immediately after the operation, pain and discomfort scores were assessed by the patients and doctor using a 10-point linear analogue scale. The stages of the operation were divided into the following: stage 1-first incision, stage 2-pterygium body excision, stage 3-conjunctival suturing, and stage 4-immediate postoperative after patching. RESULTS: There was no statistically significant difference in the mean pain scores experienced during pterygium excision (3.03+/-2.35 for the lidocaine group and 3.98+/-2.18 for the tetracaine group). However, for stage 3, there was a statistically significant difference in mean pain scores experienced during closure (P=0.03) (0.47+/-0.84 for the lidocaine gel group and 1.43+/-1.66 for the tetracaine group), with patients of group 2 experienced less pain. The mean number of additional drops required by the eyes in lidocaine gel group was also significantly (0.16+/-0.11) less than the tetracaine group (0.67+/-0.09, P=0.001). CONCLUSIONS: Topical administration of lidocaine 2% gel or tetracaine 1 % drops are both effective anaesthetic agents for primary pterygium surgery and mitomycin C. However, lidocaine gel is superior to tetracaine eye drops and its application is more convenient with a less frequent application and a sustained duration of action.

A modified technique of scleral fixated intraocular lenses for aphakic correction.

PURPOSE: To examine the safety and efficacy of a modified scleral fixated intraocular lens (SFIOL) technique combining a scleral tunnel for intraocular lens (IOL) insertion, horizontal passage of sutures, and performing anterior vitrectomy through self-sealing pars plana sclerostomies. METHODS: Retrospective review of all patients who underwent SFIOL for aphakic correction at the Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong (a tertiary referral centre) between October 2000 and December 2001 with either the modified or conventional techniques. RESULTS: A total of 20 eyes were identified. Eight modified (Group 1) and 12 conventional (Group 2) with a mean follow-up of 18.3 months. Postoperatively, all the eyes improved on unaided preoperative acuity and they all had a stable and well-positioned IOL. In all, 85% (7/8) of eyes in Group 1 maintained or improved best-corrected visual acuity. CONCLUSIONS: The modified SFIOL technique was found to be as safe and effective as conventional techniques. The main advantages of this technique include easy intraoperative suture management and superior globe maintenance.

A randomised trial comparing 0.02% mitomycin C and limbal conjunctival autograft after excision of primary pterygium.

BACKGROUND: Mitomycin C (MMC) and limbal conjunctival autograft (LCAU) are two known useful adjuvants in the prevention of pterygial recurrence. This study was conducted to compare the outcome of these two treatments. METHODS: Prospective study on consecutive cases of primary pterygium (February 2001 to March 2002) randomised into two adjuvant groups: (1) intraoperative 0.02% MMC for 5 minutes or (2) LCAU. Patients were followed for recurrence (defined as fibrovascular tissue invading the cornea >1.5mm) and complications for a period of one year. RESULTS: 115 eyes in 114 patients who completed the study were randomised to receive MMC (n = 63) and LCAU (n = 52). There were 10 recurrences (15.9%) in the MMC group and only one recurrence (1.9%) in the LCAU group. There was a statistically significant difference in the recurrence rate between the two groups (p = 0.04). There were a total of three conjunctival cysts, three symblephara, one granuloma, and one dellen. No other visually significant complications were encountered in either group. CONCLUSION: Although LCAU resulted in better one year success rates, it is technically more difficult and inapplicable in cases with previous limbal disturbance. Simple excision followed by MMC or LCAU are both safe and acceptable adjuvants for pterygium excision. Choice of adjuvant should be carefully made based on assessment of recurrence risk, local practices, and surgeon's expertise.

The use of autologous serum tears in persistent corneal epithelial defects.

PURPOSE: Persistent corneal epithelial defects (PED) present a very challenging problem to anterior segment surgeons. Autologous serum tears had been demonstrated to be beneficial in the treatment of PED. The current study was conducted to review the local spectrum of indications and to examine the outcome of autologous serum tear usage. METHODS: All cases of PED treated with autologous serum tears at a tertiary referral centre for the period August 1999 - July 2001 were identified and reviewed. RESULTS: A total of 10 eyes from 10 patients were identified (5OD : 5OS). The gender ratio was 7M : 3F and the mean age was 36.8 (range 17-73) years old. The mean duration of PED before the usage of autologous serum tears was 22.4+/-69.6 days. Six eyes healed within 2 weeks, but two eyes failed to heal after 1 month of treatment and two patients defaulted follow-up. No adverse effects were observed with the addition of autoserum tears. CONCLUSIONS: The results of the current study correlated well with previous reported studies. Autologous serum tears may be considered as a valuable adjunct in the management of recalcitrant cases of PED.

Effect of naturally occurring visual acuity differences between two eyes in stereoacuity.

Stereoacuity was measured in 30 subjects with a naturally occurring visual acuity (VA) difference between the eyes. The stereoacuity was measured by a modified Howard's apparatus using the staircase method and VA was measured with log MAR charts. Stereoacuity was worse in subjects with a large VA difference between the two eyes; the correlation between stereoacuity and VA difference was significant (r = 0.76, P < 0.001). Neither the VA of the worse eye nor of the better eye contributed to the reduction in stereoacuity. The deterioration was more obvious if VA difference between the two eyes was one line or more (correlation coefficient, r= 0.88, P < 0.001). This study also reinforces the use of a > or = 70% stereothreshold when attempt stereoacuity results to compare with other studies.

Contrasting effects of immunosuppression on herpes simplex virus type I (HSV I) induced central nervous system (CNS) demyelination in mice.

We previously reported that lip inoculation of Herpes simplex virus type I (HSV I) in specific strains of mice would induce multifocal brain demyelination (MBD). The mechanisms mediating the development of MBD are unknown. In this study, five inbred strains of mice (C57BL/6J, Balb/cByJ, A/J, SJL/J, PL/J) immunosuppressed with either irradiation (IR), cyclophosphamide (CY), or cyclosporin A (CP) along with three immune deficient strains (C57BL/6J nu/nu, Balb/cByJ nu/nu, C57BL/6J bg/bg) were lip inoculated with HSV I to determine the effect of immunosuppression on viral spread throughout the brain and the development of demyelination during the acute stage of infection. Mortality increased in all groups when compared with controls but was greatest in A/J, SJL/J, and PL/J strains, where all mice died before day 6 PI. In contrast with immunocompetent C57BL/6J mice where virus is restricted to the brainstem, virus spread throughout the brain of immunosuppressed C57BL/6J, C57BL/6J nu/nu, and C57BL/6J bg/bg mice. Despite viral spread throughout the brain of immunosuppressed C57BL/6J, C57BL/6J nu/nu, Balb/cByJ and Balb/cByJ nu/nu mice, MBD did not develop. MBD did develop however, in both HSV I infected C57BL/6J bg/bg and CP treated Balb/cByJ mice. Immunosuppression of HSV I infected Balb/cByJ mice prevents the development of demyelination at the trigeminal root entry zone (TREZ) of the brainstem while in Balb/cByJ nu/nu mice, the extent of demyelination at TREZ was reduced and delayed when compared with immunocompetent controls. These results suggest that the immune system plays an important role in limiting viral spread in the brain as well as in the development of demyelination at TREZ and of MBD throughout the brain during the acute phase of infection. Virus alone does not induce MBD in this animal model of virus induced CNS demyelination but is a prerequisite for its development.

Herpes simplex virus type I (HSV I)-induced multifocal central nervous system (CNS) demyelination in mice.

Multifocal central nervous system (CNS) demyelination develops in the brains of SJL/J, PL/J, and A/J mice following lip inoculation with a specific strain of herpes simplex virus I (HSV I). The lesions in all three inbred strains of mice share similar characteristics including demyelination, relative preservation of axons, and a mononuclear cell (MNC) infiltrate. The lesions, developing during the early phase of demyelination, also appear sequentially in the CNS (trigeminal root entry zone of the brainstem greater than cerebellum greater than cerebral hemispheres) of all three strains of mice but differ in the time of their initial appearance following infection as well as their morphology. In SJL/J mice, new areas of demyelination are observed for only 24 days following lip inoculation with virus. Late stage multifocal CNS demyelination persists throughout 28 weeks postinoculation (pi) in PL/J mice while in A/J mice the development of new areas of demyelination are restricted to 8 weeks pi. Although mononuclear inflammatory cells are present in the new areas of demyelination in either PL/J or A/J mice, viral antigens are not detected in the CNS beyond 12 days pi. In contrast, in situ hybridization studies using 35S-cDNA HSV probes and performed beyond day 12 pi identify probe-positive cells central to a number of the multifocal CNS demyelinating lesions in A/J mice. Results from studies with inbred and congenic strains of mice indicate that the major histocompatibility complex (H-2) does not determine the development of multifocal CNS demyelination following lip inoculation with HSV I but does influence the morphological appearance of the lesions that do develop.