Preventing exposure keratopathy in the critically ill: a prospective study comparing eye care regimes

Microbial keratitis has been reported among critically ill patients and the need for effective eye care in the intensive care unit (ICU) has been recognised for some time.¹ However, different eye care regimes are not always evidence based² and there is no clear consensus defining the best form of eye care. A recent survey in the United Kingdom found that 75% of ICUs used Geliperm routinely as eye care, with 25% using ocular lubricants³ Although Geliperm was originally designed as a wound dressing and there is no evidence to support its use in eye protection. Lacrilube, however, has been shown to be effective in reducing exposure keratopathy in sedated and paralysed patients.⁴ This prospective comparative study aims to assess the prevalence of corneal surface disease in ICU and the effectiveness of two different eye care regimes at preventing corneal surface disease.

Methods

Three main types of eye care are instituted at the discretion of nursing staff: (1) simple eye toilet; (2) Lacrilube alone; (3) Geliperm alone.

Patients admitted over a 4 month period were examined at weekly ophthalmology ward rounds for signs of ocular surface disease. All patients who spent less than 3 days on the unit and with primary orbital injury were excluded. The type of eye care regime was recorded as well as greatest vertical diameter of the palpebral aperture (mm), conjunctival chemosis, and length of stay. The cornea was assessed by instillation of fluorescein and viewing with cobalt blue light using an indirect ophthalmoscope and 20 dioptre lens. Corneal damage was graded from 1–6 according to severity using a previously described grading system (table 1). Conjunctival chemosis was graded from 1–3 (table 2) The sedation score and number of days that the patient were in the ICU were also recorded. Any patient found to have a compromised cornea was removed from the study and treated with prophylactic antibiotic ointment.

Table 1.

 Severity of ocular surface disease¹³

Grade I	Punctate epithelial erosions (PEEs) involving the inferior third of the cornea
Grade II	PEEs involving more than the inferior thrd of the corneal surface
Grade III	Macroepithelial defect (MED)
Grade IV	Stromal whitening in the presence of epithelial defect (SWED)
Grade V	Stromal scar
Grade VI	Microbial keratitis

Table 2.

 Severity of chemosis

Grade I	Conjunctival oedema without dellen formation
Grade II	Conjunctival oedema with dellen formation
Grade III	Conjunctival oedema with prolapse through palpebral aperture

Results

Forty seven patients were recruited. A total of 24 were found to have exposure keratopathy (50%). These results are summarised in table 3. Twenty four patients were identified who received basic eye toilet alone (no Lacrilube or geliperm). Of these, 13 patients (54%) were found to have exposure keratopathy. Thirteen patients received Lacrilube as prophylaxis and two (15%) of these patients developed exposure keratopathy. Ten patients were treated with Geliperm alone and of these nine (90%) were found to have exposure keratopathy. In general, more severe keratopathy was seen in the Geliperm group. Statistical comparison of the three groups indicated that Lacrilube is a better prophylactic measure at preventing keratopathy than basic eye care alone (Fisher’s exact test p = 0.04), and more effective than Geliperm (Fisher’s exact test p = 0.001)

Table 3.

 distribution of ocular surface disease

Simple eye toilet (n = 24)	No exposure keratopathy	11
	Grade I	4
	Grade II	6
	Grade III	3
Lacrilube (n = 13)	No exposure keratopathy	11
	Grade I	0
	Grade II	1
	Grade III	1
Geliperm (n = 10)	No exposure keratopathy	1
	Grade I	1
	Grade II	4
	Grade III	4

No significant variance was detected in the groups between sedation score (p = 0.45 Kruskal-Wallis) and number of days in the ICU (p = 0.09 Kruskal-Wallis). No skew in other ophthalmic variables, such as degree of conjunctival chemosis (Kruskall-Wallis p = 0.056) and palpebral aperture was found, with no significant variance between the groups (Kruskal-Wallis p = 0.41).

Comment

Microbial keratitis is almost always preceded by compromise of the corneal epithelium. The immune defences of the eye are predominantly innate and consist of a combination of mechanical, anatomical, physiological, and barrier defence mechanisms. These include an intact corneal epithithelium and the constant blinking action of the eyelids. The tear film also has important antimicrobial components such as lactoferrin, β lysin and immunoglobulins.⁵

ICU patients are often sedated and paralysed leading to incomplete eyelid closure. Critical illness is frequently associated with capillary leak and fluid retention that causes peripheral oedema and conjunctival oedema. As a result, these patients are susceptible to exposure keratopathy.⁶ The breakdown of the innate ocular defences of the eye is known to predispose to opportunistic infection. There have been many reports of Pseudomonas and Acinetobacter infections causing microbial keratitis among the critically ill.⁷ It is thought that procedures such as endotracheal suctioning may lead to aerosol inoculation of the susceptible patients’ corneal surface by respiratory tract organisms.^8,9 The need for effective eye care has been recognised for some time¹⁰ and although data exist to compare moist chamber treatments with ocular lubricants,^11,12 no data exist to compare the efficacy of polyacrylamide Hydrogelt (Geliperm) and ocular lubricants. We also note that Geliperm has been designed as a wound dressing and does not have a devices licence for eye care.

Our data suggest that the use of Lacrilube is more effective than Geliperm or basic eye care. Further research is clearly needed in this area.