Indian Journal of Ophthalmology

ORIGINAL ARTICLE
Year
: 2006  |  Volume : 54  |  Issue : 1  |  Page : 23--27

Herpes simplex keratitis and visual impairment: A case series


Amit Kabra1, Prajna Lalitha2, Kannan Mahadevan3, Namperumalsamy Venkatesh Prajna1, Muthaiah Srinivasan1,  
1 Departments of Cornea and Refractive Surgery, Aravind Eye Hospital and Post-graduate Institute of Ophthalmology, Madurai, India
2 Departments of Ocular Microbiology, Aravind Eye Hospital and Post-graduate Institute of Ophthalmology, Madurai, India
3 Departments of Biostatistics, Aravind Eye Hospital and Post-graduate Institute of Ophthalmology, Madurai, India

Correspondence Address:
Prajna Lalitha
Aravind Eye Hospital and Post-graduate Institute of Ophthalmology, Madurai, Tamil Nadu
India

Abstract

Purpose: T o record the natural history of herpes simplex keratitis and estimate visual impairment in eyes of patients diagnosed with herpes simplex keratitis Materials: This was a retrospective, descriptive case study for five years of the eyes of patients with clinically diagnosed herpes simplex keratitis. These patients had presented to the cornea services and a cornea specialist carried out the ocular examination under slit-lamp magnification. The medical records were reviewed by the authors. Visual acuity at presentation and clinical details on examination were recorded and, diagnosis of the stage of disease given in the case record was noted. Statistical analysis was done using chi-square-test and Fisher exact test. Results: Of a total of 212 patients (220 eyes), there were 144 males and 68 females; 118 eyes presented with stromal lesions, 44 eyes with epithelial lesions, 39 eyes with epithelial and stromal lesions, and 19 eyes with endothelitis. The improvement in visual acuity to more than 20/40 in the four clinical groups was 23 out of 44 eyes with epithelial lesion (52.27%), 83 out of the 118 eyes with stromal lesions (70.33%), 23 out of 39 eyes with epithelial and stromal lesions (58.97%), and 8 out of the 19 eyes with endothelitis (42.10%). The mean improvement in visual acuity was 3.44 lines (SD � 4.06). Conclusion: Most patients had mild disease. The majority of the patients attained the final visual acuity of 6/12 or better in the affected eye. Thus, there was only a temporary visual morbidity with fairly good functional visual outcome in majority of the patients.



How to cite this article:
Kabra A, Lalitha P, Mahadevan K, Prajna NV, Srinivasan M. Herpes simplex keratitis and visual impairment: A case series.Indian J Ophthalmol 2006;54:23-27


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Kabra A, Lalitha P, Mahadevan K, Prajna NV, Srinivasan M. Herpes simplex keratitis and visual impairment: A case series. Indian J Ophthalmol [serial online] 2006 [cited 2024 Mar 29 ];54:23-27
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Full Text

In industrialized countries herpes simplex virus (HSV) keratitis is a common and serious external ocular infection. It is said to be the most frequent, single cause of corneal opacities and subsequent visual disability and blindness, primarily because of its recurrent nature.[1] By contrast, in developing countries where prevalence of bacterial and fungal keratitis and associated ocular diseases is high, herpetic keratitis, although known to be present, is generally regarded as a less significant ophthalmic problem. The incidence of monocular blindness owing to corneal scarring and corneal opacities is estimated to be 1.5-2 million new cases every year.[2] In the developing countries, the incidence of bacterial and fungal corneal ulcers have been estimated.[3],[4] The epidemiology of ocular involvement with HSV has not been well defined in developing countries despite the observations that in developed nations, this is the most frequent cause of corneal opacity. Not much information is available regarding the visual impairment and the morbidity owing to herpes simplex keratitis in India.

The aim of this study was to study the natural history of herpes simplex keratitis and to estimate the extent of visual impairment in eyes of patients diagnosed with herpes simplex keratitis in a clinical population.

 Materials and Methods



This retrospective, descriptive case-study was carried out in a tertiary eye hospital. Approval of the Institution Review Board was obtained for collecting and reviewing data from the case records. A total of 212 (220 eyes) clinically diagnosed herpes simplex keratitis patients who presented for the first time in 1999 were included in the study. The records were maintained in a Central Medical Records Section and were computer coded and easily available for retrieval. These were cases who had presented to the Cornea Services of Aravind Eye Hospital, a tertiary eye care centre. Our institute is one of the major eye care centers in this part of South India, with facilities for advanced ophthalmic management. All the cases were examined by a cornea specialist under slit-lamp magnification.

Tracing the numbers from the database with the help of the International Classification of Diseases, diagnostic codes as herpes simplex keratitis, disciform keratitis, dendritic ulcer, and geographic ulcer, the medical records were retrieved. The details and characteristics of each patient were noted from the record, which included demographic features such as age, sex, and occupation and presenting symptoms along with duration. The number of previous attacks was also noted. Visual acuity at presentation and clinical details on slit-lamp examination were recorded and diagnosis of the stage of disease that was given in the case record was noted. Dendritic ulcer was defined as a branching, linear lesion with terminal bulbs and swollen epithelial borders.[5] The geographic ulcer was defined as an ulcer that extended through the basement membrane with swollen, scalloped, or geographic epithelial borders.[5] Stromal keratitis was defined as stromal infiltration, either immune-mediated or necrotizing, with edema.[5] Endothelitis was defined as corneal stromal edema without stromal infiltrate, but with keratic precipitates.[5] Only eyes which had typical clinical features, such as dendrites, dendrogeographic stromal keratitis, endothelitis, and keratouveitis were included in this study. Each case was followed up to the last visit of the patient or up to the year 2003, whichever was earlier. At each episode of recurrence, the visual acuity at the time of onset of recurrence and at the end of the episode was noted. The visual acuity was recorded by Snellen's method. The presence of any other comorbid ocular condition that may have been responsible for the visual impairment was also noted. None of the eyes had any associated ocular pathology.

Statistical analysis was done using chi-square-test and Fisher exact test, wherever necessary. The data were collected manually and entered in an excel program and analyzed with SAS statistical software Version 8.2 (SAS Institute, Cary, NC, USA).

 Results



The patients' ages ranged from 1 to 73 years, with a mean of 29.9 �16.69 years for females and 32.09 � 15.79 years for males. Of the total of 212 patients (220 eyes), there were 144 (68%) males and 68 (32%) females, the male-to-female ratio being 2.1 : 1. [Table 1]. Thus, majority of the patients were young, adult males. The disease was bilateral in eight patients.

Eighty-five (40.09%) patients presented between the month of January and June, whereas 127 (59.91%) patients presented between July and December. The highest number (30 patients) presented in August, whereas the lowest (nine patients) presented in February. Though more patients presented in the later half of the year, there was no clear seasonal pattern.

One hundred and sixty nine (78.77%) patients had no obvious previous attack of the disease, whereas 26 (12.26%) had one, 5 (2.36%) had two, and 12 (5.66%) had three or more previous attacks of the disease. Forty-eight (23%) patients had been treated with antibiotics, 34 (16%) patients with antiviral therapy, and 13 (16%) with steroids. Thirteen (22%) patients had used native medicine before reporting to our hospital. The common symptoms were pain, redness, defective vision, photophobia, irritation, and watering; 108 (51%) patients presented with pain, 106 (50%) with redness, and 118 (56%) presented with defective vision. The different types of clinical presentation in the 212 patients (220 eyes) were as follows: 44 of the total 220 (20%) eyes presented with purely epithelial lesions, out of which 35 were dendritic and nine were dendro-geographic ulcers. 118 eyes (53.6%) presented with purely stromal lesions, 39 (17.72%) eyes presented with epithelial and stromal lesions, and 19 (8.6%) eyes with endothelitis [Table 2]. Eighty-seven (41%) patients had one attack, 25 (12%) had two, 10 (5%) had three, and 5 (2%) had four or more attacks during the follow-up period from 1999 to 2003. The mean interval between the two attacks was 459 days between first and second attack, 378 days between second and third, 362 days between third and fourth, 600 days between fourth and fifth, 188 days between fifth and sixth, and 39 days between sixth and seventh attack.

The mean improvement in visual acuity was 3.44 lines (SD � 4.06) for all the eyes with different lesions of herpes keratitis. The change in visual acuity of the 220 eyes is given in [Table 3]. [Figure 1] shows the initial and final visual acuity in patients with epithelial lesions. Twenty-three out of 44 eyes with epithelial lesion patients (52.27%) had final visual acuity of 20/40 to 20/20. [Figure 2] shows the data in patients with stromal lesions; 83 out of the 118 eyes with stromal lesions (70.33%) had final visual acuity of 20/40 to 20/20. [Figure 3] shows the changes from the initial vs the final visual acuity in patients with epithelial and stromal keratitis. 23 out of 39 eyes with epithelial and stromal lesions (58.97%) had final visual acuity of 20/40 to 20/20. [Figure 4] shows the changes in visual acuity in patients with endothelitis. Eight out of the 19 eyes with endothelitis (42.10%) had final visual acuity of 20/40 to 20/20.

 Discussion



The true incidence of herpes simplex keratitis and ocular morbidity may be difficult to determine in a given population as some episodes of the infections may go unnoticed by the patient or may have resolved by themselves. This study describes the natural history of a chronic recurrent disease among a clinical population with special emphasis on the degree of visual loss.

The mean age of the patients in this present series of clinical population was 32 years in males and slightly lower for females, which was 29 years We do not feel this to be a significant difference. There are a few studies that have estimated the age of HSV occurrence. Darougar et al . studied primary ocular HSV infections between 1973 and 1980 in 108 patients,[6] wherein ages were represented with the mean age for the first episode of ocular HSV as being 25 years. Liesegang et al .[7] found the mean age to be 37.4 years in a study of 122 patients. There was one study conducted in South India and the mean age of patients with ocular HSV was 29 years.[8] Thus, the present evidence suggests that the common age for developing HSV is the younger adult group. The occurrence as well as the recurrence of the disease is higher in males in this study as well as in the other studies in the literature.[1],[7],[8] On analyzing the seasonal variations, as the climatic conditions of South India are more or less constant throughout the year, we did not find any clear seasonal pattern, although more cases were seen in the later part of the year. Wishart et al . in their study, though, found highest prevalence in June, but without any clear seasonal pattern during the rest of the year.[9] Pramod et al . also found no seasonal variation in India.[8]

In the present series, although nearly 80% of the patients had no obvious previous attack of viral keratitis, 20% had one or more previous attacks. In the Herpetic Eye Disease Study Group, 29% of the patients had one episode of ocular HSV, 33% had two to three episodes, and 39% had more than four or more previous episodes.[10] The other reported rates of patients having history of previous episodes are 50% and 48%.[7],[8] The reason for such a high number of patients with no obvious previous history in our series would be that some of them could have had a self-limiting disease. There is also a possibility that this could be the true scenario as ours is one of the few referral ophthalmic centers serving this region and the patients might have presented to us in the first attack itself.

We found that nearly 50% of the patients had previously used some form of medication such as antibiotics, antivirals, steroids, and native medicines. Whitcher, in his study, found 83% patients with previous antibiotic treatment, 17% with antiviral and 33% with steroid therapy.[11] In the Wilhelmus study, 26% had previous steroid therapy.[12] We do not know if this history of previous medications had any bearing on the disease outcome as this factor was not studied. But this point brings out the fact that self-medication for any red eye is definitely not appropriate and would lead to increase in the incidence of corneal blindness.

The different types of clinical presentations in this series was as follows: 15.91% presented with dendritic ulcers, 4.09% with geographic ulcers, 53.64% with stromal keratitis, 17.73% with epithelial and stromal keratitis, and 8.64% with endothelitis. The pattern of clinical presentation was not different from the various studies[7],[8],[11],[12] reported in the literature, although there was a slightly higher incidence of stromal keratitis in our study.

Blindness owing to herpes simplex keratitis is mainly owing to its recurrent nature, which leads to corneal scarring. In the present study, 41% patients had one recurrent attack during the follow-up period, 12% had two recurrent episodes, 5% had three recurrent episodes, and 2% had four or more recurrent episodes. This is consistent with those observed by Wilhelmus, in which 40% of patients experienced at least one recurrence of corneal ulceration during the five-year period.[12] In the study by Liesegang, 19.39% had one recurrent episode, 13.27% had two, 8.16% had three and four each, and 9.52% had five or more recurrent episodes, the maximum being 10 episodes in one patient.[6]

The mean interval between the attacks was progressively shorter as the number of recurrent attacks increased, exception being between fourth and fifth attack, as there was only one patient presenting with more than four recurrent episodes during the follow-up period. In the study by Wishart, the mean interval between primary and recurrent HSV ocular infection was 10 months while the intervals between second, third, and fourth attacks were very similar. But in patients with more than four attacks, the intervals were generally shorter.[9] This was similar to our study.

There was a temporary visual morbidity with fairly good functional visual outcome in majority of the patients with herpes simplex keratitis. In the present study, the extent of visual gain was as follows: 62% had visual acuity of 20/40 or more and only 2% eyes had visual acuity less than 3/200. The causes of decreased visual acuity included corneal opacity and cataract. Though the patients initially had decreased visual acuity with the acute attack of disease, the majority of the patients maintained the final visual acuity of 20/40 or better, which corresponds to the Wilhelmus study who reported that 73% had visual acuity of 20/40 or better, 24% had visual acuity between 20/60 and 20/200, and only 3% had visual acuity worse than 20/200, after 5 years of follow-up.[12] Norn reported final visual acuity of 20/20 or better in 46%, whereas 17% had visual acuity worse than 20/60.[13] Liesegang had reported 90% of 131 eyes in 122 patients had maintained 20/40 or better visual acuity throughout the course of the follow-up, and only four eyes had visual acuity worse than 20/120.[7]

There are no good criteria to judge the overall impact of this condition on the individual or on society. The condition is recurrent, and each case is unique; the patient may or may not be disabled during a recurrence and may or may not be permanently hampered by the residual corneal scar or any other structural abnormality. From this series, it could look like most patients have mild disease. Although data exist on the ocular HSV in the Western population regarding morbidity, social impact, and economic burden, no such data exist in the Indian population.[14],[15] Though prospective longitudinal studies are needed, the data from this study can nevertheless provide a basis for establishing the incidence and visual impairment owing to herpes simplex keratitis.

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