Conjunctival shrinkage and dry eye

Prevalence of conjunctival shrinkage and its association with dry eye disease: results from a population-based study in Spain

Viso E, Rodriguez-Ares MT, Bóveda FJ, et al. Cornea. 2014; 33:442-447

Conjunctival shrinkage (CS) is usually bilateral and progressive and may be caused by oculocutaneous disorders, certain drugs, chemical agents, or infections, but it may also occur in the absence of these, in otherwise healthy individuals.

This cross-sectional study looked at an age-stratified random sample of 1155 patients aged 40 years or older. The study analysed basic demographic data, medical history, indoor/outdoor occupational activity, alcohol consumption and smoking, a standardised dry eye disease (DED) symptom questionnaire and ophthalmic slit lamp evaluation. Subjects were considered symptomatic of dry eye when at least one of the following symptoms was experienced often or all of the time: dryness, sandy sensation, burning, redness, crusting of the eyelashes or sticky eyes.

The prevalence of CS was 38.2% [95% confidence interval (CI), 35.0-41.5]. Prevalence increased with aging (P < 0.001) and was not associated with gender (P = 0.696). The prevalence of symptoms, abnormal tear breakup time, fluorescein and rose bengal staining was significantly higher among subjects with CS. After controlling for age and gender, outdoor activity was directly (adjusted odds ratio 1.83) associated and high level of education was inversely (adjusted odds ratio 0.43) associated with CS. No associations with ocular or systemic diseases were found in this study of the general population, despite CS usually being associated with other disorders when seen in clinic.This study found that diagnosis of CS is simple and reproducible, that CS is strongly associated with aging and outdoor activity, and it can be used as an indicator of moderate to severe DED.My comment:

This study illustrates that CS appears to be a useful tool in the diagnosis of DED. The authors suggested it should be included in future modifications of the international dry eye workshop severity-grading scheme.

Topical tetracaine for treatment of corneal abrasions

Topical tetracaine used for 24 hours is safe and rated highly effective by patients for the treatment of pain caused by corneal abrasions: A double-blind, randomized clinical trial

Waldman N, Densie IK, and Herbison P. Acad Emerg Med. 2014; 21:374-382

This 12 month, prospective, double-blind, randomized trial was carried out at the Emergency Department (ED) of Southland Hospital, Invercargill, New Zealand. It examined whether preservative-free topical 1% tetracaine hydrochloride is effective and safe to use for 24 hours for the treatment of pain caused by corneal abrasion without delaying corneal healing. Slit lamp examination, fluorescein staining and visual acuity were performed. The control group was treated with preservative-free saline. Of 116 participants, 59 were randomized to receive tetracaine eye drops and 57 to receive saline eye drops for their uncomplicated corneal abrasion. Eye drop dosing was every 30 minutes while awake for the first 24 hours. Participants were also treated with two 500mg Paracetamol tablets four-hourly for 12 hours and preservative-free 1% chloramphenicol antibiotic eye ointment as part of the hospital department standard treatment. Patients recorded pain score measurements on a 100mm visual analogue scale (VAS) every 30 minutes for the first two hours after leaving the ED and every two hours while awake for the next 48 hours. They were asked to rate study drug effectiveness on a numeric rating scale between 0-10, with higher values indicating more effectiveness. Follow up was with repeat slit lamp examination, fluorescein staining and visual acuity performed 48 hours from the date of presentation. Telephone follow up was performed at one week and one month after presentation.

At least one follow up was completed on each of the 116 patients. No complications specifically attributed to topical anaesthetic use occurred in the 59 patients in the tetracaine group. The binomial probability confidence interval (CI) of this occurring is 95% CI of 0 – 6.1. There was no significant difference in corneal healing between the two groups as measured by the percentage of patients with persistent fluorescein uptake at 48 hours (23.9% vs 21.3%, difference = 2.6%, 95% CI = -14% to 20%, p=0.761) or persistent symptoms at 48 hours (21.7% vs 21.3%, difference = 0.4%, 95% CI = -16% to 17%, p=0.957). There was no clinical difference in VAS pain scores between the groups. Patients in the tetracaine group rated the study drugs’ overall effectiveness significantly higher compared to the control group (7.7 vs 3.9, difference = 3.9, 95%CI = 2.4 to 5.3, p<0.0005).The study concludes that topical tetracaine used for 24 hours is safe, and although there was no significant difference in patient VAS pain ratings over time, the patient surveys on overall effectiveness showed that patients perceived tetracaine to be significantly more effective than saline.My comment:

As the authors point out, concerns over human complications of topical anaesthetic use arise from old (>25 years old) case reports of unsupervised, prolonged, repeated use of high dose, preserved topical anaesthetic, or from animal or cadaver studies that may not be clinically relevant to humans. The authors also highlight the work of Verma et al, Ball et al and Ting et al, all of whom have done studies using topical anaesthetic for pain relief following PRK or corneal abrasion/trauma. These have shown no complications attributable to topical anaesthetic. This study shows that use of tetracaine at home did not mask any symptoms, cause complications, or prevent patients from returning for additional care. This suggests that prescribing a short course of topical anaesthetic, with appropriate antibiotic prophylaxis and follow up care, in order to get a patient through the initial period of pain may be a low-risk option for the treatment of pain caused by corneal abrasion. Great study and great to see our colleagues from Kew Hospital in Invercargill challenging accepted ‘wisdom’!

The season for pterygium removal

Seasonal effects on pterygium surgery outcome: Implications for the role of sunlight exposure

Sul S, Korkmaz S, Novruzlu S. Cornea. 2014; 33:504-506

This retrospective study compared the results of 55 eyes of 53 patients with primary pterygia who underwent pterygium surgery with sutured conjunctival autograft by the same surgeon in winter (December 2011-January 2012; n=32) or summer (June-July 2012; n=23). All patients were followed up for at least one year. Pterygium recurrence, ocular discomfort, persistent conjunctival inflammation, and graft complications were evaluated postoperatively. There was no significant difference between the groups with regards to age or gender. All patients were farmers in rural areas. The overall recurrence rate was 14.5%, significantly higher in the summer group compared to the winter group (26.1% vs 6.2%, P=0.048). In the summer group persistent conjunctival inflammation was significantly higher compared to the winter group (30.4% vs 6.2%, P=0.022). Pterygium recurrence was significantly higher in eyes with persistent conjunctival inflammation than in quiet eyes (66.6% vs 4.3%, P<0.001). In the summer group mild and moderate ocular discomfort was significantly greater than in the winter group (69.5% vs 34.3%, P=0.01).The authors concluded that pterygium recurrence rates were higher, and post-surgical discomfort was more common when pterygium surgery was performed in the summer compared with winter. They postulate that it is a result of increased sunlight exposure during the summer.My comment:

UV exposure is thought to be a key factor in the inflammatory cascade resulting in pterygium development, so it stands to reason it would be involved in recurrence. Nevertheless it is always good to have our long held suspicions confirmed. I recommend pterygium surgery is undertaken in winter. In fact, this is the time of year which most outdoor folk prefer!

Fingernail-induced corneal abrasions

Fingernail-induced corneal abrasions: Case series from an ophthalmology emergency department

Lin YB and Gardiner MF. Cornea. 2014. Advance online publication. doi: 10.1097/ICO.0000000000000133

Fingernail-induced corneal abrasions are a common eye injury presenting to emergency departments. This study aimed to analyse the treatment of cases of fingernail-induced corneal abrasions presenting to the Massachusetts Eye and Ear Infirmary Emergency Department and the relationship to the development of complications such as recurrent erosion syndrome and infection. A retrospective review of 99 patients presenting to the Department in 2009 with fingernail-induced corneal abrasions was performed. Patients were followed for 12 months and the demographics, nature of the injury, treatment, and complications were documented.

Average age was 29.4 (range 2-89 years). 44% (n=44) were female and 56% (n=55) were male. 39 subjects had a full 12-month follow up. 7 developed a complication from the injury. There was no difference in age or gender compared with the 32 subjects without complications. However, there was a significant difference in that adults scratched by another adult were more highly represented in the group with complications (43%, n=3/7 vs 3%, n=1/32; P=0.0017). There was no significant difference in outcome by treatment used.

The authors concluded that patients are at risk of developing complications, but there is not enough evidence-based literature available for treating this injury. They recommend that prospective trials should be performed to optimise and standardise treatments.

My comment:

Take all epithelial fingernail injuries seriously. Most will settle but patients who develop recurrent erosions face a long battle. Prescribe lots of articial tears by day and a greasy ointment at night for at least a month. Refer those who develop erosions early. There are lots of treatment options. Look carefully for any signs of underlying corneal dystrophy, especially MDF. Refer all of these patients as they do badly without agressive treatment.

Mediterranean diet and dry eye

Effect of a Mediterranean dietary pattern and vitamin D levels on dry eye syndrome

Galor A, Gerdener H, Pouyeh B et al. Cornea. 2014; 33:437-441

This cross-sectional study of 247 men from the Miami Veteran Affairs eye clinic aimed to evaluate the association between a Mediterranean dietary pattern (MeDi) and Vitamin D levels on dry eye syndrome (DES). All recruited patients in the study had normal eyelid, corneal, and conjunctival anatomy. The 2005 Block Food Frequency Questionnaire and the Dry Eye Questionnaire 5 were used, and ocular surface exam including tear osmolality (TearLab, San Diego, CA), tear break-up time (TBUT), corneal staining of punctate epithelial erosions, Schirmer strips with anaesthesia, and morphological and qualitative eyelid and meibomian gland (MG) information were performed.

The mean patient age was 69 years (range 55-95). Latent class analysis was used to categorise the presence or absence of disease and quantify its severity. It was found that adherence to the MeDi was positively associated with the risk of having DES (odd ratio 1.25, 95% confidence interval (CI), 1.06-1.47, P= 0.007) and with increasing disease severity. Vitamin D levels were not significantly associated with the presence or severity of disease. However, higher levels of Vitamin D were associated with decreased DES symptoms, with a -1.24 decrease in median Dry Eye Questionnaire 5 score for every 10-U increase in Vitamin D levels (P=0.01).

The authors conclude that adherence to the MeDi was not associated with a beneficial effect on DES. Higher Vitamin D levels had a small but favourable effect on DES symptoms.

My comment:

There is evidence to suggest that antioxidant and omega-3 supplements improve the tear film and reduce ocular surface inflammation in patients with DES. Other studies have shown a MeDi to be strongly protective against heart disease and diabetes, among other conditions, by reducing systemic inflammation. Surprisingly, in this study people following the MeDi had more severe dry eye. Unfortunately, a limitation of the cross-sectional study design is that there was no way to study the possible reason for this in more detail. Among its other roles, Vitamin D has been shown to reduce inflammation. The very small effect of Vitamin D in this study is not likely to be of clinical benefit. This study has a few limitations, and given that the findings of other studies indicate that a MeDi would be expected to have a protective effect on DES, it suggests that further studies of different design into the effect of diet on DES are warranted.

Smoking and corneal wound healing

Effects of tobacco smoking on human corneal wound healing

Jetton JA, Ding K, Kim Y and Stone DU. Cornea. 2014;33:453-456

This retrospective chart review looked at patients diagnosed with corneal abrasions and corneal ulcers from 1990 to 2010 at the Dean McGee Eye Institute. The primary outcome measure was time from initial examination to epithelial closure. Tobacco smoking was the primary exposure variable. Comorbidity variables were examined as potential confounding factors. The data was analysed using Kaplan-Meier curves and Cox proportional hazards models.

87 patients were included for corneal abrasion and 52 for keratitis. The mean healing time was 4.8 days in nonsmokers and 5.9 days in smokers in the abrasion arm, and 15.5 days in nonsmokers and 39.4 days in smokers in the keratitis arm. Comorbidities, treatment and demographic variables were controlled for. The healing time was significantly delayed in both arms of the study in smokers compared with nonsmokers (P=0.01 and P=0.03 respectively). The comorbidities were also studied after adjusting for smoking. A statistically significant delay was seen with previous keratoplasty and steroid treatment for the abrasion arm. In the keratitis arm, neurotrophic corneas and fungal infections were associated with a delay in healing after correcting for smoking.

The authors conclude that epithelial healing in smokers is delayed by 1.1 days on average compared with nonsmokers with corneal abrasions. Patients who had undergone a previous keratoplasty had delayed healing from corneal abrasions regardless of their smoking status. Epithelial healing in smokers is delayed by 23.9 days on average in patients with keratitis. Neurotrophic corneas and fungal infections also displayed delayed healing.

My comment:

Another reason to encourage your patients to stop smoking due to its detrimental effects on ocular health among other things. The injured cornea of a smoker needs to be monitored more closely and followed up over a longer period of time compared to the cornea of a non-smoker. There are limitations to this study but it is worth considering the patient’s smoking status when treating corneal injuries.