Results of pars plana vitrectomy in 24 cases of endophthalmitis.
Twenty four cases of endophthalmitis were subjected to pars plana vitrectomy. A final vitreous clearance was obtained in 62.50% cases. Visual improvement occurred in 41.67% cases. It was concluded that prompt detection and early and vigorous therapy--medical and surgical--is the mainstay in the management of endophthalmitis.
Endophthalmitis, especially the postoperative type, is the scourge of every ophthalmologist. Its blinding potential is well known. In spite of the availability of powerful anti-microbial agents and new techniques, many eyes are still lost either due to non-availability of appropriate medications and surgery, or due to a delay in administering them. The present study examines our experience with pars plana vitrectomy in the management of endophthalmitis.
During the past 3 ˝ years, 24 cases of endophthalmitis at King Edward Memorial Hospital underwent pars plana victrectomy.
Of the 24 cases, 13 were males and 11 were females. Six patients belong to the age group of 0-20 years, 3 to 21-40 years, 8 to 41- 60 years and 7 to 61-80 years. Twelve of the cases developed endophthalmitis after cataract surgery, one of the patients had intraocular lens implantation. (8 patients developed endophthalmitis at our hospital and 4 were the referred cases.) Six patients had posttraumatic endophthalmitis while rest had endogenous variety. The patients were referred to us at variable period of 1 to 14 days after the onset of symptoms.
All of them were evaluated with respect to systemic investigations, slit lamp bio microscopy and indirect ophthalmoscopy, as well as ocular investigations like B-Scan, ultra-sonography and fundus fluorescein angiography when relevant. All cases of endophthalmitis were treated as infectious, until proved otherwise. Three of the 24 cases had proven fungal infection and were treated with anti-fungal agents. The rest, were treated with antibacterial agents and steroids. Loss or absence of visualisation of the optic disc and macula, with the binocular indirect ophthalmoscope was considered as the indication to perform a pars plana vitrectomy.
In all the 24 cases, an anterior and mid-cavity vitrectomy was performed. The initial vitreous aspirates were sent for smear, culture (bacterial and fungal) and antibacterial sensitivity testing. The anti-microbial therapy was modified, based on the results of these tests.
In the three cases where vitreous aspirate produced a fungal growth on culture, an intra-vitreal injection of 5 mcg/0.1 ml of amphotericin B was given post-operatively. They were also given ketoconazole tablets, 200 mg/day, for 3 weeks,.
It may be noted that in 2 cases with postoperative endophthalmitis, a vitreous tap followed by a 0.1 ml intracameral injection of gentamicin 400 mcg and dexamethasone 360 mcg, was done pre-operatively. But both the cases eventually required vitrectomy.
Follow up period varied from 1 week to 3 years.
Due to variability in timing of presentation, only 9 were vitrectomised within 72 hours of becoming symptomatic. Eight patients took more than one week after the loss of vision.
The visual acuity, status of anterior segment and fundus, culture reports of conjunctival swab and systemic predisposing factors observed in these patients prior to vitrectomy are depicted in [Table - 1], [Table - 2], [Table - 3], [Table - 4] & [Table - 5].
The important findings are as follows:
The pre-vitrectomy visual acuity was only perception of light in 21 of the cases (with defective projection in 10) [Table - 1]. Anterior uveitis was found in 22 cases with a hypopyon in 13 [Table - 2]. The vitreous was opaque enough to obscure view of the optic disc and the macula in all the 24 cases, [Table - 3]. However, a conjunctival swab produced a positive culture in only 7 cases; Staphylococcus aureus and Pseudomonas were the commonest organisms [Table - 4]. Of the 7 cases with a positive culture, 5 were from the post-surgical endophthalmitis group. Among the systemic predisposing factors [Table - 5], diabetes mellitus was found in 5 patients with post-surgical endophthalmitis; none of the patients from the other two groups suffered from diabetes. A definite systemic predisposing factor was present in 4 of 6 patients with endogenous endophthalmitis, but none had a positive blood culture. Apart from the primary trauma itself, there was no other predisposing factor detected among the patients with posttraumatic endophthalmitis.
At the end of procedure complete clearance of the vitreous was found in 6 cases and a subtotal vitreous clearance enough to hazily visualize the retina in another 16 cases [Table - 3]. But 9 of the eyes nonetheless developed a progressive vitreous opacification. A quiet eye was achieved in 58.34% cases, a hypopyon was present in 4 of the 10 irritable eye and corneal haze was present in 8 eyes. [Table - 2]. One of the patients had a sublimated lens prior to vitrectomy and another
Apart from lens damage in 2 cases during vitrectomy, other complications observed were ciliochoroidal detachment, retinotomy and retinal haemorrhage in one case each [Table - 6].
The culture reports of vitreous aspirate are aspirate depicted in [Table - 4]. Interestingly, the 3 cases of fungal endophthalmitis were proved to be 'fungal' only by a positive fungal culture of the vitreous aspirate. Of them, 2 were post-surgical (one with an intracicular lens) and the third was a patient with endogenous endophthalmitis who was on long term steroid therapy for bronchial asthma. In our series, the visual outcome of all the 3 cases was perception of light with defective projection. Final vitreous clearance was achieved in only 1 case.
Overall, a final vitreous clearance sufficient to visualise the optic disc and macula was obtained in 15 cases [Table - 3]. As shown in Table 1, visual improvement was achieved in 10 cases (vision 6/6 to fingers counting upto 1/4 m). The vision remained the same in 11 patients (9 with perception of light with defective projection, 1 with good projection and 1 with finger counting at < lm) and was found to be deteriorated in 3 cases. Apart from persistent or progressive vitreous opacification, the main causes of poor vision included macular ederna, optic-disc pallor, cellophane maculopathy and macular haemorrhage.
A correlation of the final visual outcome, with the time interval between the onset of the symptoms and vitrectomy revealed that the better results would have been obtained if the time interval was less than 7 days. The best visual improvement was obtained when vitrectomy was done within 72 hours of the onset of the endophthalmitis. [Table - 7]
[Table - 8] illustrates the anatomical and functional outcome of pars plana vitrectomy.
The management of endophthalmitis is often fraught with failure. Initial therapy should include broad spectrum antibacterial agents and steroids, administered by topical, periocular and systemic routes. Anti-fungal agents may also be started if there is a strong clinical suspicion of fungal endophthalmitis, especially where there is history of trauma with vegetable matter, diabetes mellitus and prolonged use of steroids.
We had relatively poor results with fungal endophthalmitis; main reasons being late presentation of patients (3-7 days), delayed diagnosis (made from vitreous aspirate) and delay in availability of antifungal drugs.
Patients with mild vitreitis who respond to the initial therapy, may be continued on the medical line of treatment,. However if there is a rapidly deteriorating clinical course despite the medical therapy, we recommend that a para plana vitrectorny should be immediately performed. An urgent pars plana vitrectomy is recommended for the following situations also:
1. If the initial examination reveals profoundly diminished vision with a history of rapid deterioration,
2. If the clinical condition progresses to, or presents with, a vitreitis and hypopyon sufficient to obscure a view of the disc and macula with an indirect ophthalmoscope,
3. If there is a strong clinical suspicion of fungal endophthalmitis,
4. If there is a traumatic endophthahnitis with admixture of lens and vitreous or with a vitreitis sufficient to obscure a view of the disc and macula.
The pars plana route for vitrectomy is preferred over the limbal approach, which limits visualisation and also results in more cortical and iris trauma. In eyes suffering from endophthalmitis, a vitrectomy helps to salvage vision by 1) clearing the vitreous opacification, 2) removing the inflammatory exudates and debris, 3) removing any causative microbials and toxins, 4) enhancing the delivery of antimicrobial agents into the vitreous cavity, as well as 5) providing material for smear, culture and antibiotic sensitivity testing,.
A pre-operative vitreous tap and intracameral injection of antibiotics and steroids is recommended only for desperate cases with severe endophthalmitis, corneal decompensation and little or no salvagable vision. In most other cases, we recommend a pars plana vitrectomy if indicated.
A vitreous aspiration for microbiological tests is best done immediately after the first sclerotomy but before starting the vitreous infusion (containing antibiotic), cutting and suction. Such an aspirate may yield more positive cultures. A part of all vitreous aspirates should immediately be examined for fungal elements. If fungal elements are detected, an intracameral injection of an antifungal should be made at the end of the vitrectomy and topical and systemic antifungal agents must be started post- operatively.
During the vitrectomy, we preferred to avoid a very posterior vitrectomy as well as peeling of exudates and membranes over the retina, to avoid iatrogenic retinal tears. These can occur in endophthalmitis, as the retina tends to be edematous, necrotic and friable.
In eyes with an intraocular lens, the lens may be left behind, because there is a greater potential for damage during the procedure of removing it, than if it is left behind. Also, the fluid currents set up in the eye during a vitrectomy cleanse the intraocular lens of any microbial agents, toxins and inflammatory debris.
Post-operatively, the eye must be monitored frequently by slit lamp biomicroscopy and indirect ophthalmoscopy. A postoperative intravitreal injection of antimicrobial agents with or without steroids may be useful in cases of fungal endophthalmitis, eyes which deteriorate despite a vitrectomy, in eyes with a necrotic retina and in eyes in which an intraocular lens is left behind.
In conclusion, prompt recognition and early therapy-medical and surgical-is the most important principle in the management of endophthalmitis; it is better to overtreat initially than to undertreat or delay therapy.