visual attention impairments in alzheimer’s disease. rizzo m, anderson sw, dawson j, myers r, ball...

significant loss of fit. The overall heritability in thecombined nuclear-cataract score (the proportion of thevariance explained by genetic factors) was 48% (95%confidence interval, 42 to 54%); age accounted for 38%of the variance (95% confidence interval, 31 to 44%)and unique environmental effects for 14% (95% confi-dence interval, 12 to 18%). In conclusion, geneticeffects are important even in such a clearly age-relateddisease as nuclear cataract, explaining almost 50% ofthe variation in the severity of this disease.—Nancy J.Newman

*Twin Research and Genetic Epidemiology Unit, St. Thomas’ Hospital,Lambeth Palace Rd., London SE1 7EH, United Kingdom. E-mail:ch@twin-research.ac.uk

● The resiliency of the corneal endothelium to refractiveand intraocular surgery. Edelhauser HF.* Cornea 2000;19:263–273.

IN THIS CASTROVIEJO LECTURE, THE AUTHOR DESCRIBES

the stress factors from the corneal epithelium (phenyleph-rine and contact lenses) that can affect the corneal endothe-lium and also the effects of refractive and intraocular surgeryon the corneal endothelial structure and function. He drawsfrom his own experiments and the literature. The cornealepithelium serves as a barrier to topical phenylephrine. In acompromised epithelium, topical phenylephrine will causedrug-induced stromal edema and endothelial vacuolization.Contact lenses are capable of stimulating the epithelialarachidonic acid cascade to release arachidonic acid metab-olites that cause endothelial Na1/ K1 adenosine triphos-phatase inhibition and polymegathism. Specular microscopyof the corneal endothelial cells after refractive surgery (pho-torefractive keratectomy, laser in situ keratomileusis, intra-stromal rings) has shown minimal effect from these surgeries.However, laser ablation of the stroma within 200 mm of thecorneal endothelium will result in endothelial cell structuralchanges and the formation of the amorphous substancedeposited onto Descemet’s membrane. Phacoemulsificationwith a high flow of the irrigation solution can alter theendothelial surface glycoprotein layer, Lidocaine hydrochlo-ride (1%) used as intracameral anesthesia readily diffusesthrough the corneal endothelium, resulting in stromal uptakeand endothelial cell swelling. With phacoemulsification,however, the washout of lidocaine from the corneal and irisoccurs quickly, Corneal endothelial wound healing afterkeratoplasty occurs with migration of endothelial cells, devel-opment of tight junctions, and the formation of Na1/ K1

ATPase pump sites. The author concludes that cornealendothelial resiliency is due to the increased peripheralendothelial cell number for migration, the ability of endothe-lial cells to form tight junctions in order to maintain theendothelial barrier, the increase in endothelial of Na1/ K1

ATPase pump sites under stress, and the ability of the corneal

endothelial cells to shift their metabolism of glucose to thehexose monophosphate shunt for the production of nicotin-amide adenosine dinucleotide phosphate and membranerepair.—Thomas J. Liesegang

*Department of Ophthalmology, Emory Eye Center, Suite B2600, 1365BClifton Road NE, Atlanta, GA 30022. E-mail: ophthfe@emory.edu

● Nontraumatic corneal perforation. Lekskul M, FrachtHU, Cohen EJ,* Rapuano CJ, Laibson PR. Cornea 2000;19:313–319.

THE AUTHORS STUDIED THE PREDISPOSING CONDI-

tions, treatments, and visual outcomes of nontrau-matic corneal perforations with a retrospective chartreview of patients between 1992 and 1998. A total of 40nontraumatic corneal perforations were analyzed. Sixty-two percent of the cases were female. At presentation, 35of 40 eyes (87.5%) has best corrected visual acuity of20/200 or worse. The most common diseases associatedwith perforation were keratoconjunctivitis sicca (12 eyes),bacterial keratitis (6 eyes), exposure keratopathy (5 eyes),and herpes simplex virus keratitis (4 eyes). Visual acuityimproved in three of eight eyes treated with penetratingkeratoplasty, five of 14 eyes treated with tissue adhesive,and one of 12 eyes given medical treatment. After allowingfor the different levels of presenting vision, treatmentmodality was not significantly related to final visual out-come. The authors conclude that keratoconjunctivitissicca is the most common underlying disease associatedwith nontraumatic corneal perforation. Corneal perfora-tions were managed successfully using tissue adhesive,medical therapy, or penetrating keratoplasty. Treatmentdepended on the characteristic of the perforation and onthe visual potential of the eye.—Thomas J. Liesegang

*Cornea Service, Wills Eye hospital, 900 Walnut Street, Philadelphia,PA 19107. E-mail: ejcohen@hslc.org

● Visual attention impairments in Alzheimer’s disease.Rizzo M,* Anderson SW, Dawson J, Myers R, Ball K.Neurology 2000;54:1954–1959.

IMPAIRED ATTENTION CAN HINDER INFORMATION PROCESS-

ing at multiple levels and may explain aspects of functionaldecline in aging and dementia. Impairments of visual atten-tion in early Alzheimer’s disease (AD) may contribute toperformance reductions in other cognitive domains, includ-ing memory and executive functions. The authors analyzedthe scores on a battery of tests of attention and cognitiveabilities in 64 older individuals, 42 with mild AD and 22control subjects without dementia, testing the hypothesesthat patients with AD would have impairments of visualattention, and that these impairments would correlate with

AMERICAN JOURNAL OF OPHTHALMOLOGY384 SEPTEMBER 2000

dysfunction in other key cognitive domains. Patients withAD performed significantly worse than control subjects onmeasures of sustained attention, divided attention, selectiveattention, and visual processing speed. The differences werenot due to differences in age, education, or basic visualfunction. Strong relationships were identified between re-duced attention skills and overall cognitive impairment.They conclude that deterioration of attention abilities occursin early stages of AD, and likely contributes to functionaldecline in these patients. More routine assessment of visualattention deficits could give a more accurate measure offunctionally useful perception in patients with AD who shownormal visual acuity and visual fields, perhaps providinguseful clues to diagnosis and staging.—Nancy J. Newman

*Division of Behavioral Neurology and Cognitive Neuroscience, Depart-ment of Neurology, The University of Iowa Hospitals and Clinics, IowaCity, IA 52242. E-mail: matthew-rizzo@uiowa.edu

● Conjunctiva-associated lymphoid tissue in the humaneye. Knop N, Knop E.* Invest Ophthalmol Vis Sci 2000;42:1270–1279.

MUCOSA-ASSOCIATED LYMPHOID TISSUE REPRESENT A

part of the immune system located at mucosa sur-faces. The authors investigated its occurrence, compo-nents, topography, and functional significance in thehuman conjunctiva and lacrimal drainage system. Fifty-three complete conjunctival sacs were obtained fromcadaveric eyes, prepared as flat wholemounts, stained,optically cleared, observed in total thickness, and sec-tioned for light microscopic histology, immunochemistry,and electron microscopy. Eight lacrimal sacs were preparedsimilarly. Lymphoid tissue was mainly observed in thepalpebral conjunctiva, more pronounced in the upper thanin the lower lid. In all specimens, diffuse lymphoid tissue oflymphocytes and plasma cells, most of which were IgApositive, formed a thin layer in the lamina propria. Theoverlying epithelium produced secretory components. Inapproximately three fifths of the conjunctival sacs, orga-nized follicular accumulations were embedded in this layer.They had a lenticular shape, were composed of B-lympho-cytes, and were apically covered by lymphoepithelium.Both types could be associated with the conjunctivalcrypts. Lymphoid tissue with similar characteristics, in-cluding secondary follicles, was also observed inside thelacrimal drainage system. High endothelial venules werepresent in all types of lymphoid tissue. The authorsconclude that human conjunctiva and lacrimal drainagesystems show an associated lymphoid tissue that containsall the components necessary for a complete immuneresponse. Expression of immunoglobulins and secretorycomponent indicates that the conjunctiva belongs to thesecretory immune system.—Thomas J. Liesegang

*Department of Cell Biology in Anatomy, Medical School Hannover,D-30625 Hannover, Germany. E-mail: knop.erich@mh-hannover.de

● Flow cytometric analysis of inflammatory markers inconjunctival epithelial cells in patients with dry eyes.Brignole F, Pisella P-J, Goldschild M, De Saint Jean M,Goguel A, Baudouin C. Invest Ophthalmol Vis Sci 2000;41:1356–1363.

THE AUTHORS INVESTIGATED THE EXPRESSION OF IN-

flammatory and apoptosis-related markers by conjunc-tival epithelial cells from patients with dry eye.Immunologic anomalies were identified at baseline, beforetreatment with a masked medication, in a homogeneousseries of patients with dry eye syndrome who were enrolledin a large European multicenter clinical trial (CyclosporinA Dry Eye Study; Allergan, Irvine, CA). Impressioncytology specimens were collected in 243 patients withmoderate to severe keratoconjunctivitis sicca (KCS), withor without Sjogren syndrome (SS). Fifty normal subjectswere separately examined to provide normal control val-ues. Specimens were analyzed in a masked manner by flowcytometry, using antibodies directed to markers of theimmune system and /or apoptotic pathway: HLA DR,CD40, CD40 ligand, Fas, and APO2.7. Levels of expres-sion were quantified, and results were compared with thoseobtained in the 50 normal patients. One hundred sixty-nine specimens were successfully interpreted at baseline,including 41% from patients with SS. A highly significantincrease of HLA DR expression by conjunctival cells wasfound in KCS-affected eyes compared with normal eyes,who did not express this marker or did so very weakly.HLA DR expression in eyes with SS was significantlyhigher than in KCS-affected eyes without SS. Fas andAPO2.7 were found at low levels in all normal andKCS-affected eyes. CD40 and CD40 ligand expressionswere significantly increased in eyes with KCS comparedwith normal eyes. HLA DR, CD40 and Fas were found atsignificantly higher levels in the SS group than in thenon-SS group. The authors conclude that conjunctivalcells from patients with dry eye with moderate to severeKCS, with or without SS, overexpress inflammatory andapoptosis-related markers. Whether inflammation is aprimary phenomenon in KCS or is the consequence ofrepetitive abrasion of the ocular surface after tear filmdeficiency remains to be determined. The authors felt thisdata supports the use of immunomodulatory and /or anti-inflammatory drugs in the treatment of patients withKCS.—Thomas J. Liesegang

*Ambroise Pare Hospital, Department of Ophthalmology, 9 avenueCharles d Gaulle, 92104 Boulogne/ Seine Cedex, France. E-mail:arepo@worldnet.fr

ABSTRACTSVOL. 130, NO. 3 385