Protective barrier effect of the posterior lens capsule in ...iovs.arvojournals.org/pdfaccess.ashx?url=/data/journals/iovs/... · 108 INVESTIGATIVE OPHTHALMOLOGY 6 VISUAL SCIENCE

108 INVESTIGATIVE OPHTHALMOLOGY 6 VISUAL SCIENCE / January 1984 Vol. 25

inhibits the appearance of PMNs in the aqueous humorundoubtedly inhibits inflammatory responses in theeye.'' However, because of the difficulty in obtainingrepresentative samples of aqueous humor, it is con-ceivable that less potent but potentially useful anti-inflammatory compounds, which are evaluated in thisway, could be overlooked.

Key words: inflammation, endotoxin, eye, polymorphonu-clear leukocytes, myeloperoxidase, aqueous humor, iris-ciliarybody

Acknowledgment. The authors thank Mrs. E. Paterson forexcellent editorial assistance.

From the Department of Ophthalmology, University of ColoradoHealth Sciences Center, Denver, Colorado. Supported by USPHSresearch grant number EY04716 from the National Eye Institute.Submitted for publication April 6, 1983. Reprint requests: Dr.R. N. Williams, Box B205, UCHSC, 4200 E. 9th Avenue, Denver,CO 80262.

References

1. O'Connor GR: The inflammatory response. In Immunology ofthe Eye, Workshop III, Suran A, Gery I, and Nussenblatt RB,editors. Special Suppl. Immunology Abstracts. London, IRLPress, 1981, pp. 225-229.

2. Bolliger GA, Kupferman A, and Leibowitz HM: Quantitation

of anterior chamber inflammation and its response to therapy.Arch Ophthalmol 98:1110, 1980.

3. Gallin JI: Granulocyte adherence. In The Cell Biology of In-flammation, Glynn LE, Houck JC, and Weissman G, editors.Amsterdam, Elsevier/North Holland, 1980, 299-355.

4. Williams RN, Paterson CA, Eakins KE, and Bhattacherjee P:Quantification of ocular inflammation: evaluation of polymor-phonuclear leucocyte infiltration by measuring myeloperoxidaseactivity. Curr Eye Res 2:465, 1983.

5. Bradley PP, Priebat DA, Christensen RD, and Rothstein G:Measurement of cutaneous inflammation: estimation of neu-trophil content with an enzyme marker. J Invest Dermatol78:206, 1982.

6. Smith JW and Castro GA: Relation of peroxidase activity ingut mucosa to inflammation. Am J Physiol 234:R72, 1978.

7. Lowry OH, Rosebrough NJ, Farr AL, and Randall RJ: Proteinmeasurement with the Folin phenol reagent. J Biol Chem193:265, 1951.

8. Bito LZ: The effects of experimental uveids on anterior uvealprostaglandin transport and aqueous humor composition. InvestOphthalmol 13:959, 1974.

9. Bhattacherjee P, Williams RN, and Eakins KE: An evaluationof ocular inflammation following the injection of bacterial en-dotoxin into the rat foot pad. Invest Ophthalmol Vis Sci 24:196,1983.

10. Higgs GA, Flower RJ, and Vane JR: A new approach to anti-inflammatory drugs. Biochem Pharmacol 28:1959, 1979.

11. Kulkarni PS, Bhattacherjee P, Eakins KE, and Srinivasan BD:Anti-inflammatory effects of betamethasone phosphate, dexa-methasone phosphate and indomethacin on rabbit ocular in-flammation induced by bovine serum albumin. Curr Eye Res1:43, 1981.

Protective Barrier Effect of the Posterior Lens Capsule in Exogenous

Bacterial Endophthalmitis—An Experimental Primate Study

Todd L. Beyer, George Vogler, Dion Sharma, and Francis E. O'Donnell, Jr.

Ten eyes of five Rhesus monkeys underwent extracapsularlens extraction. The right eye of each monkey was allowedto retain an intact posterior capsule. The left eye of eachmonkey had a wide primary capsulectomy with minimal an-terior vitrectomy. In order to exclude operative contamination,we waited 2 to 3 weeks later to challenge the eyes withbacteria. Seventy-two hours after anterior chamber injectionof equal numbers of Staphylococcus aureus, diagnostic cul-tures were obtained from the anterior chamber and vitreousand correlated with the clinical findings. Injection of 10,000S. aureus produced culture-positive endophthalmitis in eyesthat had undergone posterior capsulectomy, but it failed toproduce endophthalmitis in fellow eyes with intact posteriorcapsules. This suggest that a significant barrier effect againstthe development of bacterial endophthalmitis exists in theeyes with intact posterior capsules. Invest Ophthalmol VisSci 25:108-112, 1984

Exogenous, bacterial endophthalmitis is a disastrouscomplication of intraocular surgery. Visual prognosis

in this disease remains relatively poor even with ag-gressive therapeutic intervention using intracameralantibiotics and early vitrectomy.1"3 The best treatmentremains prevention. Recently there has been renewedinterest in extracapsular cataract extraction techniques,primarily because of the popularity of posterior cham-ber intraocular implants. It is the purpose of this in-vestigation to evaluate the role that the primate pos-terior capsule may play in inhibiting the developmentof endophthalmitis by confining the infected materialto the anterior chamber. A barrier effect of the posteriorcapsule in the rabbit model has been previously sug-gested by Katz and Forster in an unpublished com-munication.

Materials and Methods. Ten eyes of five monkeysunderwent extracapsular cataract extraction. On theday prior to the operative procedures, each monkeywas examined, while under ketamine sedation, for lens,retinal, or vitreous abnormalities with the direct and

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No. 1 Reports 109

indirect ophthalmoscopes. At the end of the exami-nation, the periorbital hair was removed and the eye-lashes trimmed. A generous amount of 0.5% chlor-amphenicol ointment was applied to each eye. On theday of surgery, each monkey was given a preoperativeinjection of ketamine and then administered a generalanesthetic utilizing halothane and oxygen. The eyesof each monkey were then dilated with 2.5% phenyl-epherine and 1% cyclopentolate. The entire face, botheyelids and lid margins were then prepped carefullywith povidone-iodine and the conjunctival forniceswere irrigated with sterile saline. Next, sterile drapeswere applied and a pediatric wire lid speculum inserted.A 4-0 silk suture was then passed beneath the superiorrectus muscle and clamped to the drape with a sterilehemostat. A fornix-based conjunctival flap was fash-ioned under microscopic control and bleeders cauter-ized with bipolar wet-field cautery.

A grooved incision was made with a razor bladeand two horizontal 8-0 silk mattress sutures were pre-placed at the 1:00 and 11:00 o'clock positions. A smallpuncture into the anterior chamber was made withthe razor blade and an irrigating cystotome was insertedfor the large (7 mm) round anterior capsulotomy. Thepreplaced sutures were looped to the side and the in-cision was extended and completed with curved leftand right corneal scissors. The soft nucleus was ex-pressed as completely as possible, and then the woundwas closed by tying the preplaced sutures. The anteriorchamber was reformed with balanced salt solution,and the cortex was removed completely with the 0.2mm aspiration tip Mclntyre needle on a 6-cc Monojectsyringe. The posterior capsule of each right eye waskept completely intact. At this point, each left eyeunderwent a primary capsulectomy of at least 5-7-mm diameters utilizing the cystotome and the Kauf-man vitrector. The anterior vitreous was left undis-turbed if possible. No peripheral iridectomies wereperformed. The wound was then closed with inter-rupted 8-0 silk suture and the fornix-based conjunctivalflap hooded over the incision and anchored with 6-0plain gut suture. Each eye received gentamicin sulfate10 mg and triamcinalone 2.5 mg, subconjunctivally,at the end of the procedure. A combination steroid/antibiotic and atropine 1% ointments were applied,and the animals were returned to their cages.

After a period of 2 weeks, all eyes were re-examinedand clinical findings recorded. All eyes were found tobe quiet with clear media. Conjunctival chemosisand/or hyperemia were absent. No eye had any clinicalsign of endophthalmitis.

The inocula for intraocular injection were preparedin the following manner. A strain of Staphylococcusaureus (25923) was obtained from the American TypeCulture Collection. The culture was monitored peri-

odically for purity. Organisms were maintained onBlood Agar plates, (St. Louis Biological Laboratories,Inc., St. Louis, Missouri) and subcultured every 72hours to assure viability. Twenty-four-hour-old cultureswere used in preparing the inocula for all animal ex-periments. At prescribed time intervals, 24 hour cul-tures of the above described organisms were suspendedin sterile saline. To assure a single cell suspension, thepreparations were subjected to a vortex mixer for 30seconds. Cell counts were performed by diluting thevortexed suspensions in sterile saline with a Tri-Lyne(Dade) erythrocyte pipette. The diluted suspensionswere counted in a Neubauer hemocytometer. Appro-priate dilutions were made accordingly to obtain 103

or 104 organisms/0.05 cc sterile saline. Microbial con-centrations were verified at the time of preparation byinoculating known volumes of the supension on bloodagar plates and performing counts after 24 hours. Anadditional inoculation was made onto blood agar platesat the same time as anterior chamber injection to assureviability of the inocula.

After ketamine HCL injection, each monkey wasbrought to the operating suite, where a topical anes-thetic agent was administered and a wire pediatricspeculum inserted. A bevel up injection was carefullymade into the anterior chamber through the surgicalwound adjacent to one of the silk mattress sutures witha 27-gauge needle on a 0.5 cc calibrated tuberculinsyringe (Fig. 1). Both eyes of monkey # 1 received asingle injection of a suspension of 1,000 Staphylococcusaureus organisms in 0.05 cc saline into the anteriorchamber. The needle was carefully withdrawn, and acotton tip applicator gently applied to minimize leak-age. The remaining four monkeys (#2-#5) received aninjection of 10,000 organisms/0.05 cc at 2Vi to 3 weekspost-lens extraction.

After inoculation, each animal was examined bytwo observers who had no previous knowledge as towhich eye had been capsulectomized. Their clinicalhandlight exams were recorded every 24 hours for 72hours (Fig. 2). At 72 hours after inoculation, all animalswere sacrificed, and the anterior chamber and centralvitreous cavities were separately cultured using aseptictechniques.

Results. (Tables 1 and 2). Monkey #1 had inocu-lation of each eye with 1,000 Staphylococcus aureusorganisms and failed to develop anything more thana mild anterior chamber reaction in both eyes, whichcleared totally within 48 hours. Cultures of both theanterior chamber and vitreous in both eyes were sterileat 72 hours.

The remaining 8 monkey eyes were inoculated with10,000 Staphyloccocus aureus organisms, and each lefteye developed a clinically obvious endophthalmitiswithin 72 hours (Fig. 2). Most often this was obvious


110 INVESTIGATIVE OPHTHALMOLOGY b VISUAL SCIENCE / January 1984 Vol. 25

iiFig. 1. Technique of anterior chamber inoculation with Staphylococcus aureus. A, in right eye with intact posterior capsule and B, in the

left eye, which had a posterior capsulectomy.

at 48 hours, and it was characterized by the presenceof marked edema, chemosis, purulent conjunctivaldrainage, corneal haze with vitreous opacification, andpupillary membranes. As time progressed, all left eyesgot much worse. In contrast, all right eyes developedan anterior chamber reaction greatest at 24 hours,which proceeded to clear rapidly by 72 hours. The

vitreous remained clear. No lid edema, purulent con-junctival drainage, corneal haze, pupillary membrane,or vitreous opacification developed in any of the righteyes. At the time of sacrifice (72 hours post injection),all eyes (right and left) had light growth or no growthfrom anterior chamber aspirates. Eyes with intact pos-terior capsules had no growth from the central vitreous

Table 1. Clinical findings

Monkey

#1OD

OS

#2OD

OS

#3OD

OS

#4OD

OS

#5OD

OS

# Bacteria injectedinto AC

103

103

10*

10*

10*

10*

10*

10*

10*

10*

24 hours afterinoculation

Moderate AC reaction











Mild AC reaction

Mild AC reaction


Endophthalmitis

Media clear

Endophthalmitis

Media clear

Endophthalmitis

Media clear

Endophthalmitis


Media clear

Media clear

Media clear

Endophthalmitis

Media clear

Endophthalmitis

Media clear

Endophthalmitis

Media clear

Endophthalmitis


No, 1 Reports 111

cavity. All eyes with posterior capsulectomy had pos-itive cultures from the central vitreous cavity.

Discussion. It is apparent from this experimentalstudy that the posterior lens capsule inhibits the de-velopment of vitreous infection. It would seem likelythat this is due to a barrier effect, which helps to confinethe bacteria to the anterior chamber. As in the humansituation, we found that the anterior chamber aspiratecould be negative despite heavy growth from the vit-reous aspirate.4 Apparently, the anterior chamber isbetter able to control bacterial infection than is thevitreous cavity. Noteworthy is the fact that three righteyes (animals 2, 3, 5) had positive cultures from theanterior chamber aspirate despite a negative vitreousculture and negative clinical appearance for endo-phthalmitis. This finding suggests that it is valuable toobtain both anterior chamber and vitreous cultures,especially in cases of early suspected endophthalmitisafter extracapsular surgery where microorganisms mayyet be confined to the anterior chamber.

Although this experimental study demonstrates theability of the intact posterior capsule to inhibit spreadof infection, it would be wrong to extrapolate fromthis study to the clinical situation and to conclude thatplanned extracapsular surgery with an intact posteriorcapsule is less likely to cause bacterial endophthalmitisthan is intracapsular surgery. In general, when authorshave compared intracapsular infection rates to extra-capsular rates, they were comparing intracapsular tounplanned extracapsular rates. Allen, Mangiaracine,and others reported the incidence of postoperative in-fection was increased with extracapsular surgery, themajority of which were unplanned.56 Similarly, Christyand Lall reported an unplanned extracapsular infectionrate of 1.31% that was three times higher than theirintracapsular series of 0.41%.8 They felt that increasedintraocular manipulation associated with an unplannedextracapsular extraction predisposed to a greater riskof exogenous endophthalmitis.

It seems doubtful that the infection rate for un-planned, extracapsular extractions is equivalent to thatof modern, planned extracapsular extraction. For ex-ample, infection rates have been reviewed in the ex-tracapsular technique of phacoemulsification. Mc-Reynolds reported an incidence of 0.4% (2 in 500 cases)of infectious endophthalmitis following phacoemul-sification.9 These cases were associated with a vitreouswick syndrome. Kratz reported an incidence of bac-terial endophthalmitis of 0.1 % in a large series of 2,000cases of phacoemulsification, of which an unspecifiednumber had received a primary capsulotomy or cap-sulectomy.10 It may be that modern, planned extra-capsular surgery, performed using appropriate preppingand draping, which excludes contaminated lashes andlid margins from the operative field, and executed un-

Table 2.

Monkey

#1ODOS

#2ODOS

#3ODOS

#4ODOS

#5ODOS

Culture findings

# Bacteriainoculated

into AC

103

103

104

10*

10"10"

10"10"

10"10"

Anterior chamber(AC) culture at

72 hours

NegativeNegative

Light growthLight growth


NegativeNegative


Vitreousculture at72 hours

NegativeNegative

NegativeModerate growth

NegativeLight growth

NegativeHeavy growth

NegativeHeavy growth

der microscopic control, thus allowing for more com-plete removal of cortical material while reducing thepossibility of inadvertent disruption of the posteriorlens capsule and resultant admixture of formed vit-reous, does reduce the chances of bacterial endo-

Fig. 2. Clinical appearance at 72 hours of monkey #4, demon-strating the absence of external signs of endophthalmitis in the righteye, which has an intact posterior capsule, and the presence of obviousclinical endophthalmitis in the left eye, which had a posterior cap-sulectomy.


112 INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE / January 1984 Vol. 25

phthalmitis in comparison to an intracapsular oper-ation. The answer to this very important questionwould require a large clinical series, since the incidenceof bacterial endophthalmitis is fortunately low.

There is a significant barrier effect produced by anintact posterior lens capsule, which inhibits the spreadof bacterial infection from the anterior chamber to thevitreous cavity in the primate model. It is not possiblefrom the data obtained in this study to answer thecontroversy over whether or not modern extracapsularsurgery is superior to intracapsular surgery in the pre-vention of bacterial endophthalmitis. Despite thedemonstration of a significant barrier effect to endo-phthalmitis produced by the posterior lens capsule, thetwo techniques probably vary in the frequency and/or size of inadvertent bacterial inocula introduced dur-ing surgery. A large, multicenter clinical study is nec-essary to answer this important question.

Key words: Endophthalomitis, cataract, posterior capsule

Acknowledgments. The authors gratefully acknowledge theassistance of James Stoutenburg, Ophthalmic Photographer,and Nadine Sokol, Ophthalmic Illustrator, in the preparationof this manuscript.

From the Bethesda Eye Institute and the Departments of Oph-thalmology and Comparative Medicine, St. Louis University, Schoolof Medicine, and the Bethesda General Hospital, St. Louis, Missouri.Supported in part by a research development grant from Researchto Prevent Blindness, Inc., and from the Golden Fund, BethesdaEye Institute, Department of Ophthalmology, St. Louis UniversitySchool of Medicine. Submitted for publication January 28, 1983.

Reprint requests: Francis E. O'Donnell, Jr., M.D., Bethesda EyeInstitute, 3655 Vista, St. Louis, MO 63110.

References1. Vastine DW, Peyman GA, and Guth SB: Visual prognosis in

bacterial endophthalmitis treated with imtravitreal antibiotics.Ophthalmic Surg 10:76, 1979.

2. Peyman GA, Raichand M, and Bennett TO: Management ofendophthalmitis with pars plana vitrectomy. Br J Ophthalmol64:472, 1980.

3. Forster RK: Endophthalmitis. Diagnostic cultures and visualresults. Arch Ophthalmol 92:387, 1974.

4. Records RE: Early postoperative endophthalmitis: current con-cepts of therapy. Eye, Ear, Nose, Throat Monthly. 46:874, 1967.

5. Allen HF and Mangiaracine AB: Bacterial endophthalmitis aftercataract extraction. A study of 22 infections in 20,000 operations.Arch Ophthalmol 72:454, 1964.

6. Allen HF and Mangiaracine AB: Bacterial endophthalmitis aftercataract extraction. II. Incidence in 36,000 consecutive operationswith special reference to preoperative topical antibiotics. TransAm Acad Ophthalmol Otolaryngol 77:581, 1973.

7. Locatcher-Khorazo D and Gutierrez E: Eye infections followingcataract extraction with special reference to the role of staph-ylococcus aureus. Am J Ophthalmol 41:981, 1956.

8. Christy NE and Lall P: Postoperative endophthalmitis followingcataract surgery. Effects of subconjunctival antibiotics and otherfactors. Arch Ophthalmol 90:361, 1973.

9. McReynolds WU: Phacoemulsification by a country practitioner.In Current Concepts in Cataract Surgery. Selected Proceedingsof the Fourth Biennial Cataract Surgical Congress, Emery JMand Paton D, editors. St. Louis, C.V. Mosby Co., 1976, pp.119-120.

10. Kratz RP: Teaching Phacoemulsification in California and 2000cases of Phacoemulsification. In Current Concepts in CataractSurgery. Selected Proceedings of the Fourth Biennial CataractSurgical Congress. Emery JM and Paton D, editors. St. Louis,C.V. Mosby Co., 1976, pp. 121-123.

Characterization of Somatostatin-like immunoreactivityin Vertebrate Retinas

David Marshak* and Tadaraka Yamada-f

Large differences in retinal concentration of somatostatin-like immunoreactivity (SLI) were observed even amongclosely related species. Hog and chicken retinas, like thoseof goldfish and frog described previously, contained roughlyequal amounts of SLI coeluting with somatostatin tetra-decapeptide (SI4) and octacosapeptide (S28) on SephadexG 50 chromatography. In contrast, virtually all of the SLIfrom rat retina coeluted with S14, and nearly all of the bovineretinal SLI coeluted with S28. These species differences mayreflect differences in post-translational processing of the var-ious molecular forms of retinal SLI. Invest Ophthalmol VisSci 25:112-115, 1984.

Somatostatin-like immunoreactivity (SLI) in theretina has many of the properties of neurotransmitters

SLI is synthesized in the retina1 and stored in its in-trinsic neurons (review in reference 2). Retinal SLIcan be released by depolarizing stimuli in the presenceof calcium, apparently by the same mechanism as neu-rotransmitters and other secretagogues.3 The retina isan excellent system to test whether somatostatin du-plicates the natural transmitter's actions on postsyn-aptic cells. Such studies would be facilitated by elu-cidation of the structures of retinal SLI. This surveyof retinal SLI in various vertebrates provides prelim-inary information about the structures of these mol-ecules.

Materials and Methods. Eyes from cows, rabbits,chickens and carp were dissected within 5 min of death


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Protective barrier effect of the posterior lens capsule in ...iovs.arvojournals.org/pdfaccess.ashx?url=/data/journals/iovs/... · 108 INVESTIGATIVE OPHTHALMOLOGY 6 VISUAL SCIENCE