Bacterial I<eratitis after Radial Keratotomy AI.ICE Y. MATOBA, MD,1 JAIME TORRES, MD,2 KIRK R. WILHELMUS, MD,2

M. BOWES HAMILL, MD/ DAN B. JONES, MD2

Abstract: The authors identified nine patients with culture-proven keratitis after radial keratotomy (RK). Three patients became infected in the immediate post­operative period, and six patients had delayed-onset keratitis. Gram-negative rods were the predominant pathogens in late-onset keratitis (4 of 6 infections). Gram-positive cocci were implicated in all three early postoperative infections. The inferior corneal quadrants were involved in seven of nine patients. Two episodes of late-onset keratitis were associated with contact lens wear. Five of these patients had transverse incisions or greater than eight radial cuts. All six patients regained visual acuity of 20/40 or better. Two additional cases of early­onset and six cases of late-onset keratitis with many features similar to these cases have been reported previously. Ophthalmology 96:1171-1175, 1989

The infectious complications of radial keratotomy (RK) include keratitis1

-7 and rarely endophthalmitis. 8 Postop­

erative keratitis can be divided into two types: early onset (occurring in the immediate postoperative period) and late onset (occurring months or even years after surgery). We present nine cases of corneal infection after RK (3 early onset and 6 late onset; one of the latter has been reported previously1

). A review ofRK-associated culture­proven keratitis cases that have been reported in the lit­erature is also included.

PATIENTS

Our cases of early-onset keratitis are summarized in Table 1. Gram-positive cocci (2 Staphylococcus aureus and l Streptococcus pneumoniae) were found in all cases. All patients had infiltrates in the inferior quadrants. One patient had perforation of the 6-o'clock incision intra­operatively with infection at that site.

Originally received: February 3, 1989. Manuscript accepted: February 20, 1989.

1 Houston Veterans Administration Medical Center, Houston.

2 Cullen Eye Institute, Baylor College of Medicine, Houston.

Presented as a poster at the American Academy of Ophthalmology Annual Meeting, Las Vegas, October 1988.

Supported in part by VA Medical Research funds.

Reprint requests to Alice Y. Matoba, MD, Cullen Eye Institute. Baylor College of Medicine, 6501 Fannin St, Houston, TX 77030.

The six cases of late-onset keratitis are summarized in Table 2. Four infections were due to gram-negative rods, with Pseudomonas aeruginosa in two cases. Propionibac­terium acnes (Fig 1) and Mycobacterium chelonae (Fig 2) were found in the rest of the cases. Two infections were associated with contact lens wear, and one patient had a history of trauma (chemical injury 2 months beforP pre­sentation). Five patients had transverse incisions or more than eight radial incisions. In all three patients with trans­verse incisions, the infiltrate involved at least one trans­verse cut. Four of the six infiltrates involved the inferior quadrant; two patients had infiltrates at a transverse in­cision located in a superior quadrant. All patients achieved a visual acuity of 20/40 or better. Astigmatic error ranged from 0 to +4.75 diopters (D). Only two patients had as1ig­matism greater than 1.5 D. In most cases, keratometry readings were not available.

CASE REPORT

A 4 7 -year-old woman had a 1-day history of irritation of the left eye 2 years after a three-incision RK (Table 2, patient 4-L). Results of slit-lamp biomicroscopic examination showed a small infiltrate within the 7:30-o'clock incision, with minimal edema of the surrounding stroma (Fig 3). The focus of infection (too small to be scraped easily with a Kimura spatula) was drained with a 25-gauge needle, used to inoculate the culture media. Enterohacter gergoviae, a recently identified species which has been isolated from various environmental sources including cosmetics and water, was found. 9 Decompression of the focal abscess and topical therapy with gentamicin 13.6 mg/ml at one drop every 30 minutes resolved the infection within I week. Uncorrected visual acuity returned to 20/15.

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OPHTHALMOLOGY • AUGUST 1989 • VOLUME 96 • NUMBER 8

Table 1. Early-onset Keratitis after Radial Keratotomy

Patient No./ Age (yrs)/Sex

Time of Onset Trauma/Predisposition

1.5-mm perforation at 6:00 intraoperatively

Radial Cut/ Transverse Cut

8 radial

Site (clock hr)

6:00

Final Visual

Organism Acuity

Staphylococcus 20/25 au reus

1-E*/33/F

2-E/31/F

3-E/29/M

10 days

3 days 16 radial 9:00 Streptococcus pneumoniae

2 wks 8 radial 7:00 S. aureus 2 transverse at 85°

* Previously reported .1

Table 2. Late-onset Keratitis after Radial Keratotomy

Time of Patient No./ Onset Contact Lens

Wear Predisposing

Factor Radial Cut/ Site Final Visual

Age (yrs)/Sex (yrs) Transverse Cut (clock hr) Organism Acuity /Refraction

1-L/32/F 2 16 radial 3:00 Pseudomonas 20/30/-3.00 aeruginosa

2-L/35/M 2 Hard 8 radial; transverse at 11:00 Propionibacterium 20/40/-1.00 3:00, 4:30, 11 :00, acnes + 4.75 X 95 12:00

3-L/34/M 2 Chemical injury 2 mos earlier

8 radial; transverse at 5:00 Mycobacterium 20/40/-1.00 5:00, 11:00 chelonae

4-L/47/F 2 5-L/24/F 3 Rigid gas

permeable

3 radial 18 radial

7:30 Enterobacter gergoviae 20/15/Piano 6:00 Serratia liquefaciens 20/20/-4.75

+1.50 X 85 6-L/39/M 5 Acquired immune

deficiency syndrome

8 radial; transverse at 12:00 P. aeruginosa 20/30/-1.00 12:00

DISCUSSION

A review of the literature showed two additional cases of early-onset (Table 3) and six oflate-onset keratitis (Ta­ble 4). Early-onset keratitis is probably influenced by the risk factors which are common to all ophthalmologic sur­gical procedures: intraoperative or immediate postoper­ative exposure of the wound to pathogens. Three of five reported cases were due to gram-positive cocci, commonly encountered after cataract extraction. The two cases of M. chelonae keratitis, previously reported by Robin and associates,2 may have been due to a common source; both patients had surgery within a few weeks of each other in the same physician's office. All five cases had infiltrates in the inferior quadrants, although intraoperative factors predisposing to infection might be expected to affect all quadrants equally. In both of the patients with transverse incisions, the infiltrate was located at a transverse cut (Figs 4, 5).

There are 13 cases of late-onset keratitis after RK in 12 patients reported in the literature. Eight of these were due to gram-negative rods, with P. aeruginosa in six cases. In addition S. epidermidis was found in three cases, and

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+2.75 X 135

M. chelonae and P. acnes in one case each. Six infections were associated with contact lens wear. Four patients had potential predisposing factors such as recurrent erosion syndrome that developed after RK (2 cases), chemical injury, or acquired immune deficiency syndrome. Eight patients had either transverse incisions or more than eight radial incisions. One patient had a deepening procedure 6 months after the original RK. In all three patients with transverse cuts, the infection involved at least one trans­verse incision. Eleven of 13 keratitis cases involved the inferior quadrants; in two the infection occurred in su­perior quadrants at the site of the transverse cuts. Eleven patients achieved a visual acuity of 20/40 or better; seven had a visual acuity of 20/20 or better.

Late-onset RK-associated infectious keratitis is prob­ably influenced by factors intrinsic to this procedure. Many authors have documented delayed wound healing after RK and noted the presence of epithelial ingrowth and epithelial cysts within RK wounds. 10

•11 As previously

observed there may be a breakdown of the epithelial ridges overlying RK incisions leading to development of post­operative recurrent erosions.5

•11 Transverse incisions,

particularly when they cross a radial incision, are suscep­tible to gaping.4 They may also increase susceptibility to infection by transsecting corneal nerves and creating cor-

MA TOBA et al • BACTERIAL KERATITIS AFTER RK

neal anesthesia within the incision. 12 More than eight ra­dial cuts may compromise corneal integrity. The tendency for the inferior quadrants to be involved may be due to factors such as exposure and surface drying. In both early­and late-onset keratitis cases, 17 of 19 infections involved the inferior quadrants (Fig 6).

Of 12 patients with late-onset keratitis, patient 4-L is particularly interesting. This patient had a three-incision RK with no other potential risk factors such as contact lens wear or trauma. Her infection was localized to the

Fig I. Top left, late-onset keratitis culture-positive for Propionibacterium acnes. A superior transverse incision was involved (patient 2-L). Fig 2. Top right, late-onset keratitis culture-positive for Mycobacterium che­lonae. The transverse incision at 5:00 o'clock is involved (patient 3-L). Fig 3. Center left, late-onset keratitis culture-positive for Enterobacter gergoviae. The inflammatory material was localized to the incision site, with minimal extension into the surrounding stroma (patient 4-L). Fig 4. Bottom right, early-onset keratitis culture-positive for Streptococcus pneumoniae. The infiltrate extends from 6:30 to 10 o'clock, encompassing six radial incisions and one transverse incision (patient 2-E). Fig 5. Bottom left, early-onset keratitis culture-positive for Staphylococcus aureus. The 7-o'clock transverse incision is involved (patient 3-E).

incision (Fig 3 ). Although epithelialization of the wound may have predisposed the cornea to poor healing with increased susceptibility to wound gape and inoculation of pathogens, the presence of the epithelial lining may also have acted as a barrier to lateral spread of the infec­tion, with relative sparing of the adjoining stroma.

The etiologic agents of infectious keratitis after RK in­clude anaerobic bacteria (P. acnes) and nontuberculous mycobacteria (M. chelonae: 3 of 17 cases). We screen all suspect corneal scrapings with acridine orange stain, a

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Reference

Robin et al2 (1986)

References

Shivitz and Arrowsmith4

(1986)

Mandelbaum et al5

(1986)

O'Day et al3 (1986)

lnsler and Semple6

(1988) McClellan et al7

(1988)

• 0

o• •

OPHTHALMOLOGY • AUGUST 1989 • VOLUME 96 • NUMBER 8

Table 3. Early-onset Keratitis after Radial Keratotomy: Literature Cases

Age (yrs)/ Time of Onset Radial Cut/ Site Final Visual Sex (wks) Transverse Cut (clock hr) Organism Acuity

36/F 2 12 radial; transverse 3:30, 7:30 M. chelonae 20/40 at 3:00, 9:00

33/F 2 8 radial 4:00 M. chelonae

Table 4. Late-onset Keratitis after Radial Keratotomy: Literature Cases

Age (yrs)/ Time of Contact Lens Sex

28/F

35/F

29/F

54/F

21/M

21/M

0

Onset

35 mas

40 mas

7 mas

2 yrs

2 yrs

27 mas

2 yrs

0

Wear

Rigid gas permeable

Rigid gas permeable

Extended wear soft

Therapeutic soft

0

• 0 •

0 0 0 o ooo •

Predisposing Factor

Recurrent erosions

Recurrent erosions

Radial Cut/ Site Final Visual Acuity I Transverse Cut (clock hr) Organism Refraction

8 radial 5:00 P. aeruginosa 20/20

6:00 P. aeruginosa 20/20

8 radial 7:30 P. aeruginosa 20/16/+1.00 +.50 X 135

16 radial (8 at 5:30 Staphylococcus 20/16/-2.00 +.75 6 mas) epidermidis X 40

16 radial 5:30 P. aeruginosa 20/50 (deepened at 6 mas)

16 radial (8 at 4:30 S. epidermidis 20/20 4 mas)

8 radial 4:30 S. epidermidis 20/15/-1.50 (deepened at later date)

fluorochromatic dye which binds to nucleic acids of bac­teria (including mycobacteria), fungi, and Acanthamoe­bae. It is more sensitive than the Gram stain to evaluate bacterial keratitis. 13

•14 Once an organism has been de­

tected, more specific stains can be used to characterize it better. Specimens can be cultured on anaerobic media such as Schaedler's medium or Brucella agar in addition to conventional media for bacteria and fungi. If acid-fast organisms are detected, or the clinical features of the ker­atitis suggest a relatively indolent organism resistant to conventional antibiotics, media for mycobacteria such as Lowenstein-Jensen or Middlebrook can be used.

• Early Onset 0 Late Onset

The complications of RK have been well documented by many authors. Late-onset infectious keratitis is prob­ably influenced by the slow healing process characteris­tically noted in eyes that have undergone RK. The de­velopment of recurrent erosions, wound gape, and corneal anesthesia in transverse incisions may all increase the sus­ceptibility of the cornea to infection. Any postoperative manipulation of the ocular surface, including fitting con­tact lenses, should be done with caution. We support the opinion expressed by O'Day and associates3 that the pa­tient contemplating this elective surgery should have a full understanding of the risk of ocular complications. Patients who have undergone RK should be considered to have a long-term compromise of their ocular surface.

Fig 6. Location of infectious keratitis after RK. Seventeen of 19 infections were located in inferior quadrants.

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MA TOBA et al • BACTERIAL KERATITIS AFTER RK

REFERENCES

1. Wilhelmus KR, HamburgS. Bacterial keratitis following radial keratot­omy. Cornea 1983; 2:143-6.

2. Robin JB, Beatty RF, Dunn S, et al. Mycobacterium chelonei keratitis after radial keratotomy. Am J Ophthalmol1986; 102:72-9.

3. O'Day OM, Feman SS, Elliott JH. Visual impairment following radial keratotomy: a cluster of cases. Ophthalmology 1986; 93:319-26.

4. Shivitz lA Arrowsmith PN. Delayed keratitis after radial keratotomy. Arch Ophthalmol 1986; 104:1153-5.

5. Mandelbaum S, Waring GO, Forster RK, et al. Late development of ulcerative keratitis in radial keratotomy scars. Arch Ophthalmol1986; 104:1156-60.

6. lnsler MS, Semple HC. Delayed microbial keratitis following radial ker­atotomy. CLAO J 1988; 14:163-4.

7. McClellan KA, Bernard PJ, Gregory-Roberts JC, Billson FA. Suppurative

keratitis: a late complication of radial keratotomy. J Cataract Refract Surg 1988; 14:317-20.

8. Gelender H, Flynn HW Jr, Mandelbaum SH. Bacterial endophthalmitis resulting from radial keratotomy. Am J Ophthalmol1982; 93:323-6.

9. Richard C. Genes VI. Enterobacter.ln: Krieg NR, Holt JG, eds. Bergey's Manual of Systemic Bacteriology. Vol. 1. Baltimore: Williams & Wilkins, 1984; 469.

10. Deg JK, Zavala EY, Binder PS. Delayed corneal wound healing fol­lowing radial keratotomy. Ophthalmology 1985; 92:734-40.

11. Jester JV, Villasenor RA, Miyashiro J. Ephthelial inclusion cysts fol­lowing radial keratotomy. Arch Ophthalmol1983; 101:611-5.

12. Shivitz lA, Arrowsmith PN. Corneal sensitivity after radial keratotomy. Ophthalmology 1988; 95:827-32.

13. McCarthy LR, Senne JE. Evaluation of acridine orange stain for de­tection of microorganisms in blood cultures. J Clin Microbial 1980; 11:281-5.

14. Gomez JT, Robinson NM, Osato MS, Wilhelmus KR. Comparison of acridine orange and Grarn stains in bacterial keratitis. Am J Ophthalmol 1988; 106:735-7.

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