Published in American Academy Of Ophthalmology(January-April),2009

There are approximately 125 million CL wearers in the

world. It is estimated that in India there are around 1 million contact lens wearers. Approximately 30% to 50% of contact lens (CL) wearers report dry eye symptoms . Meibomian gland dysfunction has been recognized as a possible cause of CL related dry eye. CL use induces various complications , including infection, allergic conjunctivitis, corneal disorders, and dry eye . Dry eye is particularly troubling because 30-50%of CL wearers report dry eye for which causative mechanisms have been proposed including inflammation , increased evaporation and osmolarity of the tear film, and dewetting of the CL surface.

PURPOSE : This study investigated the influence of

CL wear on the meibomian glands using a newly developed meibographic technique.

Design: Cross-sectional observational case series .

METHODS AND MATERIALS PARTICIPANTS :Contact lens wearers(n=121; 47 men , 74

women ; mean age = 31.8 years) and healthy volunteers(n=137;71 men ,66 women; mean age =31.4 years). The entry criteria for CL wearers included volunteers who had been wearing contact lenses for atleast one year and had no evidence of ocular diseases other than those associated with CL related changes. The entry criteria for control group included volunteers who had not worn CL and had no ocular diseases.

The following tests were performed : slit lamp examination of the eyelids , corneal and conjunctival stain using fluorescein measurement of the tear film break up time , evaluation of the meibomian glands using noncontact meibography and measurement of the tear production using the Schirmer test.

Lid margin abnormalities were scored from 0 to 4 based on

the presence of 4 criteria : irregular lid margin ,vascular engorgement , plugging of the meibomian gland orifices , and shift of the mucocutaneous junction. The SPK staining was graded as 0(no staining),1( mild staining with a few disseminated stains and limited to less than 1/3rd of the cornea),2(moderate staining with severity between 1 and 3),3(severe staining with confluent stains and occupying half or more of the cornea) The tear film break up time was measured 3 consecutive times after the instillation of fluorescein. Upper and lower eyelids were turned over and the meibomian glands were observed with the novel noncontact infrared meibographic method .

Partial or complete loss of the meibomian glands

was scored using the following grades (meiboscores)for each eyelid: Grade 0(no loss of meibomian glands ) Grade 1 ( the affected area was less than 33% of the area occupied by the meibomian glands ) Grade 2( affected area was between 33% and 66% of the area occupied by meibomian glands) Grade 3 (affected area was more than 66% of the area occupied by meibomian glands). Meiboscores for upper and lower eyelids were summed for each eye.

The average score for SPK and lid margin abnormality ,

the average TBUT, and Schirmer value in CL wearers and non wearers were compared using Mann-Whitney U test .

Observations & Results The mean SPK scores in CL wearers and non-wearers

were 0.58 and 0.13, respectively. The mean scores for the lid margin abnormalities in CL wearers and non-wearers were 0.40 and 0.24,respectively. The mean TBUT in CL wearers and non-wearers were 4.8 and 6.7 seconds, respectively. The mean Schirmers values in CL wearers and nonwearers were 20.4 and 20.2 , respectively.

Figure A, (representative of RGP group)

In a 23-year-old man who had used rigid gas-permeable CLs for 8 years, most meibomian glands in both the upper and lower eyelids were shortened. The areas in which meibomian glands were absent are encircled with dotted white lines. The shortening of the meibomian glands began not from the orifice side but from the distal side.

Figure B, (representative of hydrogel CLs group) In a 28 year old woman who had used hydrogel CLs for 12 years , shortening and dropout of meibomian glands were observed in both the upper and lower eyelids. The areas where meibomian glands were absent are encircled with dotted white lines.

Figure C (representative of control group) A 29-year-old nonwearer. Shortening or dropout of meibomian glands was not observed.

CL wearers showed shortened clusters of meibomian glands .

The shortening of these glands occurred not at the side with orifices ,but instead was observed on the distal side . The average upper eyelid, lower eyelid, and total meiboscores in CL wearers were significantly higher than those in non wearers. The average differences between the meiboscores of CL wearers and non wearers in the upper and lower eyelids were 0.54 and 0.25,respectively. This suggests that wearing of CL produces different effects on the upper and lower eyelids ( upper>> lower). There was no significant difference in the average meiboscores from RGP lens wearers and hydrogel lens wearers . The duration of CL wear was the only variable that was significantly associated with the meiboscores.

The meiboscore was significantly higher in CL wearers than in the control group. The average meiboscore of CL wearers was similar to that of a 60-69 year old age group from the normal population. A significant positive correlation was observed between the duration of CL wear and the meiboscore.

DISCUSSION: Aging increased the severity of meibomain gland

changes in normal individuals. Both aging and CL wear produce similar effects on meibomain glands . These results suggest that CL wear accelerates agerelated changes in the meibomain glands. This study also shows that lens material do not play a significant role in CL relate dry eye.

Two hypothesis have been proposed for the causative mechanism for meibomian gland loss in CL wearers: 1. Ong and Larke suggested that mechanical trauma from the CLs causes duct blockage in the meibomian glands. 2. Henriquez and Korb suggested that meibomian gland dysfunction is a result of the aggregation of desquamated epithelial cells at the orifice of the glands.

The shortening of the meibomian glands in CL

wearers began from the distal side. These results suggest that chronic irritation of these glands by CLs through conjunctiva is major causative mechanism for these gland changes in CLs wearers. The decrease in these glands were greater in the upper eyelids ,as it experiences more irritation because it makes larger movements during blinking. These results show that dry eye resulting from increased evaporation of the tear film is more prevalent in CL wearers than in non wearers .

CONCLUSION: CL wear is associated with a decrease in

the number of functional meibomian glands . This decrease is proportional to the duration of CL wear and contribute to dry eye in CL wearers.

- Published in American Academy Of Ophthalmology(January-April),2009

Endophthalmitis is a rare but serious postoperative

complication of cataract surgery. Many studies have estimated rates and identified risk factors for the condition but these studies are often limited by a small number of cases or by data collected over many years , resulting in outcome ascertainment difficulties .

AIM:The objective of study was to identify risk factors for suspected acute endophthalmitis after cataract surgery.

Methods & Materials: Design: Population based retrospective cohort study

Participants: Administrative data from more than

4,40,000 consecutive cataract surgeries in Ontario, Canada, from April 1,2002, to March 31 , 2006.

Methods: Consecutive physicians billing claims for cataract surgery and specific intra-operative and postoperative procedures related to complications of cataract surgery were identified . Acute endophthalmitis was defined using surrogate markers for intra-ocular infections, including vitrectomy, vitreous injection or aspiration procedures not in combanation with air or fluid exchange or dislocated lens extraction , performed 1 to 14 days after cataract surgery . Anterior vitrectomy was used as a surrogate marker for capsular rupture.

The procedure of air or fluid exchange was used as a

surrogate marker for retinal detachment,and the procedure of dislocated lens extraction was used as a surrogate marker for lost lens / lens fragments. Anterior vitrectomy on the same day as the cataract surgery was used as a surrogate marker for capsular rupture. They thus calculated overall rates of endophthalmitis and rates grouped by patient demographics (age,sex, socioeconomic status, and residence), surgical facility, season, year,and association with capsular rupture.

Results: There were 617 suspected acute endophthalmitis cases of

4,42,000 cataract surgeries over the 4 years . The overall unadjusted and adjusted rates of suspected acute endophthalmitis were both 1.4 per 1000 cataract surgeries. Men had higher rates than women with an adjusted odds ratio of 1.40. The oldest age group (85 years)had the highest rate and the youngest group(20-64)had the second highest rate. The endophthalmitis rates for these age groups were significantly different from those in 65-84 years age group . The endophthalmitis rates were approximately 10 fold higher in those with capsular rupture compared with those without.

Figure 1. Age- and sex-specific rates of acure suspected endophthalmitis.

Figure 2 . Annual age- and sex-adjusted rates of acute suspected endophthalmitis.

Figure 3. Age- and sex-adjusted rates of acute suspected endophthalmitis by season.

Discussion: Overall rate of suspected acute endophthalmitis was found to be 1.4 per

1000. Rate was higher in men and there was no trend from young to old. No difference was found in annual rates , between seasons,or between rural or non-rural communities ,there was no trend in patient socioeconomic status. This study found a 40% higher odds of developing endophthalmitis in men compared with women.this could be a result of differences in populations, age distributions. This new finding requires further investigations as previous studies showed no difference in rates between men and women . Surgical facility rates ranged from 0 to 4.5 per 1000 cataract surgeries. More than 75% facilities had a rate lower than 2.16 per 1000 . There were no more than 4 endophthalmitis cases within any 4 week period at any facility over the study period.

Table 1. Summary of Endophthalmitis Rates from Recent Large Studies

CONCLUSIONS: The overall rates of suspected acute endophthalmitis

are low but significantly higher in certain patient groups. Our population-based analysis can be used as a benchmark for quality-improvement initiatives and can assist clinicians in educating their patients regarding the risks associated with cataract surgery. Future work is required to address the higher rate of endophthalmitis in men, those with capsular rupture, and yhe oldest patients undergoing cataract surgery.