Corneal blindness is a major public health problem in India and infections constitute the most predominant cause. Varicella-zoster virus was detected by a polymerase chain reaction-based assay in the aqueous of the left eye; however, neither cytomegalovirus nor herpes simplex virus DNA were detected by polymerase chain reaction-based assays. Using the polymerase chain reaction, we have demonstrated the presence of VZV DNA in the cornea of a patient who underwent penetrating keratoplasty 2 years following development of HZO. Varicella-zoster virus was detected by a polymerase chain reaction-based assay in the aqueous of the left eye; however, neither cytomegalovirus nor herpes simplex virus DNA were detected by polymerase chain reaction-based assays. Untreated dendritic keratitis may cause permanent scarring of the cornea with impaired vision or blindness. The local use of dexamethasone over a prolonged period may lead in some cases to secondary glaucoma and the development of complicated cataract. To be used, therefore, under strict medical supervision.
Abuse of topical steroids . Ocular surface disease : – Lagophthalmos ( Corneal exposure ) . Many types of bacterial corneal ulcers look alike and vary only in severity. The onset of illness is sudden with fever, malaise and severe neuralgic pain along the course of the affected nerve. Speight, GS. 2- Contact lens wearer : the commonest here is pseudomonas . However, some general clinical descriptions may be useful.
_ Diphtheria . _ Listeria . _ Hemophilus aegypticus . 3- Viral : The commonest is Herpes Simplex Virus ( HSV ) . 4- Fungal : _ Candida in Immunocompromised patients . _ Filamentous eg : aspergillus especially with wood or plant trauma . 5- Acanthamoeba : Which exist in two forms trophozoite and cyst especially in water .
• Source of infection: 1- Dacryocystitis : the commonest organism is pneumococcus . Pseudomonas corneal ulcer begins as a gray or yellow infiltrate at the site of a break in the corneal epithelium (Figure 6-2). Ocular complications usually appear at the subsidence of skin eruptions and may present as a combination of two or more of the following lesions: 1. 4- Contact lens Bad habits with contact lens wear are common sources for acanthamoeba keratitis such as improper cleaning using tap water , homemade saline , saliva or wearing while swimming . • In Viral ( Dendritic ) Keratitis with HSV : 1- Atropine only in sever uveitis . Haemorrhagic hypopyon is attributed to either Pneumococcal or Herpes simplex viral keratitis. 3- Topical steroids under umbrella of antiviral in stromal not epithelial.
4- Bandage , contact lubricants . 5- We may use antibiotics to prevent secondary infection . 6- No Hot foments . 7- Surgical Debridement if resistant and Keratoplasty if there is scar . • In disciform Keratitis : topical steroids are used together with the antiviral drugs . • In Herpes Zoster Ophthalmicus : Systemic antiviral drugs : _ Acyclovir ( 800mg 5 times daily for 7 days ) . _ Famcyclovir – valacyclovir ( 500mg 3 times daily ) .
M liquefaciens (diplobacillus of Petit) causes an indolent oval ulcer that usually affects the inferior cornea and progresses into the deep stroma over a period of days. _ Maintenance dose : Hourly around the clock for 48 hours then gradual tapering accordingly till improvement . 2- Fortified : Around the clock ( each every 30 minutes ) for 48 hours then taper accordingly. *Subconjunctival antibiotics ; may be given if there is weak compliance . It begins at the midperiphery of healthy cornea in the exposed areas. Complications we use Gram stain . Blood agar in culture which is a good media for fungi and bacteria except : • Neisseria • Moraxella for which we use chocolate agar .
• Hemophilus _ In anaerobic organisms : cooked meat broth . # Sensitivity test : Takes 1-2 days , 7-14 days . # Disk diffusion method to determine if the organism is : • Susceptible • Intermediate • Resistant To acertain antibiotic _ In non responsive ulcers : _ stop the treatment for 24 hrs . _ rescrap . _ use Zn stain and Lowenstein – Jensen stain . Fungal # Staining PAS or Cacofluor white . Scrapings may contain gram-positive cocci-singly, in pairs, or in chains.
# Culture Non-nutrient agar + dead E.coli .