VOL. 84, NO. 2 CORRESPONDENCE 273

2. Smelser, G. K., and Silver, S.: The distribution of mast cells in the normal eye. Exp. Eye Res. 2:134, 1963.

Storage Conditions of Corneal Endothelium

Editor: In their article, "Corneal endothelium

under various storage conditions" (Am. J. Ophthalmol., 83:206, 1977), by R. Geer-aets, W. D. McLester, and F. D. McMul-lan, the authors conclude that in the rab­bit cornea using MK or minimum essen­tial medium (MEM) with 10% calf serum, "storage under refrigeration leads to bet­ter results than storage in an incubator at 37°C." In addition, they found M-K medi­um to be superior to MEM with serum after six to nine days' storage.

These results are not in agreement with research by us and others where scanning (SEM) and transmission (TEM) electro-microscopy show that storage in M-K medium at 4°C does not reliably preserve human endothelium for longer than 96 hours1,2 while human corneas stored in 37°C organ culture (OC) using MEM with 10% calf serum and 1% L-glutamine re­tain active glucose metabolism3 and in­tact endothelial4,5 and epithelial6 ultra-structure for up to 37 days. Our research, as well as that of Cintron7 and Yanoff,8

shows that the addition of 4 to 10% serum to culture medium enhances endothelial and epithelial preservation during OC at 37°C.

Several factors may explain the differ­ence in these results. First, as the authors state, their " . . . observations cannot be extrapolated to stored human donor mate­rial since several variables exist . . . " in­cluding species difference. In our re­search we have found that the rabbit is a poor model for investigation of OC corne­al preservation (especially at 37°C) and that results obtained using this animal

correlate poorly with those obtained using human tissue. As an alternative, we have found the cat cornea to be a superior model for studying corneal storage and our results with this species correlate well with human data.

Secondly, Geeraets, McLester, and McMullan studied endothelial structure by SEM only with no TEM to confirm the state of the cytoplasmic ultrastructure and micro-organelles. We have found that SEM alone is often misleading because a normal appearing endothelial monolayer seen by SEM often shows marked ultra-structural abnormalities when studied with TEM. In addition, the authors do not state if they warmed the rabbit cor­neas stored at 4°C to 35°C for two hours' incubation before fixing for SEM. If not, their evidence of normal SEM in 4°C stored corneas is not meaningful since Van Horn, Schultz, and Debrun1 showed that dead endothelial cells often retain a normal appearance by SEM unless incu­bated at physiologic temperatures for two hours before fixation.

Finally, the authors do not state the amount of medium used during their 37°C OC. We assume they used either the standard M-K vial containing 20 ml of medium or a petri dish containing ap­proximately 15 ml of medium. Geroski and Edelhauser9 showed that the whole rabbit cornea utilizes glucose at a rate of 113 |x/hr/cornea and produces lactate at the rate of 104 fi/hr/cornea at 37°C. Since both M-K and MEM media contain ap­proximately 100 mg/100 ml of glucose, a rabbit cornea stored in 20 ml of medium at 37°C would completely exhaust the glucose supply between days 6 and 7. Also, by day 9 the medium lactate con­centration would reach over 125 mg/100 ml. This loss of metabolic subtrate and accumulation of toxic metabolic waste products may explain the onset of rabbit endothelial cell destruction noted in their

274 AMERICAN JOURNAL OF OPHTHALMOLOGY AUGUST, 1977

study after six to nine days' storage. To preserve corneal structure and function during intermediate or long-term 37°C O.C. storage one must either change the medium every two to three days or use a large initial medium volume.

RICHARD L. LINDSTROM, M.D. DONALD J. DOUGHMAN, M.D.

Minneapolis, Minnesota

REFERENCES 1. Van Horn, D. L., Schultz, R. O., and Debrun, R.

O.: Endothelial survival in corneal tissue stored in M-K medium. Am. J. Ophthalmol. 80:642, 1975.

2. Aquavella, J. V., Van Horn, D. L., and Hagger-ty, C. J.: Corneal preservation using M-K medium. Am. J. Ophthalmol. 80:791, 1975.

3. Lindstrom, R. L., Doughman, D. J., Van Horn, D. L., Dancil, D., and Harris, J. E.: A metabolic and electron microscopic study of human organ cultured cornea. Am. J. Ophthalmol. 82:72, 1976.

4. Doughman, D. J., Van Horn, D. L., Harris, J. E., Miller, G. E., Lindstrom, R. L., Summerlin, W., and Good, R. A.: Endothelium of the human organ cultured cornea. An electron microscopic study. Trans. Am. Ophthalmol. Soc. 81:304, 1973.

5. : The ultrastructure of human organ cul­tured cornea. 1. Endothelium. Arch. Ophthalmol. 92:516, 1974.

6. Van Horn, D. L., Doughman, D. J., Harris, J. E., Miller, G. E., Lindstrom, R. L., Summerlin, W., and Good, R. A.: The ultrastructure of human organ cultured cornea. 2. Stroma and epithelium. Arch. Ophthalmol. 93:275, 1975.

7. Cintron, C: Organ culture of chick embryonic cornea. Develop. Biol. 27:100, 1972.

8. Yanoff, M.: In vitro biology of corneal epitheli­um and endothelium. Trans. Am. Ophthalmol. Soc. 73:571, 1975.

9. Georski, D. H., and Edelhauser, H. F.: Meta­bolic evaluation of cryo-preserved corneal tissue. Arch. Ophthalmol. 91:130, 1974.

Iridocyclisis Associated with Juvenile Rheumatoid Arthritis

Editor: An article by S. N. Key III and S. J.

Kimura, "Iridocyclitis associated with ju­venile rheumatoid arthritis (JRA)" (Am j Ophthalmol. 80:425, 1975), escaped our attention until recently. Nevertheless, we feel obliged to comment on this report, particularly on the statement that "anti-inflammatory therapy with corticoste-roids does not seem to alter materially the

course of the JRA-associated ocular in­flammation."

In our experience, the majority of chil­dren with iridocyclitis from juvenile rheumatoid arthritis do respond to treat­ment with ophthalmic corticosteroids and mydriatics.1,2 A report by Chylack and associates1 disclosed that close to 40% of episodes of iridocyclitis responded promptly to therapy with ophthalmic mydriatics and corticosteroids while an­other 10% responded more slowly or from three to six months. The remaining pa­tients needed therapy for more than six months. In only 10 of 72 eyes was visual acuity reduced to less than 20/200.

Why then the discrepancy between their results and ours? Key and Kimura provide one explanation in their state­ment that "structural damage was already too advanced (in their cases) to permit a fair judgment of these agents." The un­usually high frequency of late sequelae among their patients, including posterior synechiae (61%), band keratopathy (49%), and cataract (58%), as well as the disclo­sure that eight eyes required surgery to control glaucoma, support this view.

Of the 45 patients with juvenile rheu­matoid arthritis initially seen for iridocy­clitis by Key and Kimura, only 28 were available for reexamination when their current report was compiled. Conse­quently, 17 or 38% of their patients were lost to follow-up. On the basis of this alarmingly high dropout rate alone, we could argue that their therapeutic conclu­sions are open to question.

•One of the most striking observations about the iridocyclitis of juvenile rheu­matoid arthritis is that it appears and recurs primarily in patients with the least amount of joint involvement. From 25 to 40% of patients with pauciarticular (oli-goarticular) juvenile rheumatoid arthritis (swelling of only one to four joints) will develop iridocyclitis on long-term follow-up.1-3-4

Key and Kimura do not mention the