Drug side effects seen in clinical ophthalmology are divided into two types. The first comprises those induced by drugs administered for ocular diseases, and the second, those induced by drugs given for non-ocular diseases. Among cases of ocular side effects which were reported in scientific journals in Japan between 1956 and 1988, the most frequently seen were those induced by chemotherapeutics, steroids, several kinds of ophthalmic solutions and agents affecting central nervous system. Of recent problematic drugs with related ocular side effects, ophthalmic solution of β-blocker for cardiovascular events, cyclopentrate for psychological disturbance, anaesthetics for corneal damage, fluorescein-Na for sudden death or shock, ethambutol for optic neuropathy, oral contraceptives for disturbance of retinal circulation and steroids for cataracts and serous choroidretipathy should be paid special attention.

To detect ocular side effects induced by administered drugs as early as possible, ophthalmologists who care for the patients should always have enough knowledge about the drug and periodic examinations should be performed.

Experimental studies concerning drug toxicity on ocular tissues performed by the author's lab were briefly introduced. They were i. drug-toxicity test utilizing a cultured human conjunctival cells, ii. the influence of drug-affinity with melanin pigment which correlates with intraocular drug dynamic mode and iii. how to detect drug induced changes in the crystalline lens.

Crj: CD系，16週齢のラット1匹にretinal dysplasia, typical colobomaおよびretinoceleを併発した眼病変を観察した。その眼底像に於いて左右対称に内眼角下側部位に乳頭を含む境界明瞭の灰白色部位，視神経乳頭の拡張および硝子体動脈遺残が認められた。その病理所見は，網膜外顆粒層および内顆粒層のロゼット形成を含む配列異常，視細胞層，色素上皮層および脈絡膜血管の欠損，網膜の眼窩外への嵌入，および硝子体動脈遺残を伴った網膜細動脈のループ形成であった。これら所見の原因として，胎生期眼杯裂閉鎖障害が推察されている⁸⁾。

そこで我々はこれら病変の成因を明らかにするために胎生期のラットおよびマウスを用い，Ochratoxin Aを投与し実験的に眼杯裂閉鎖障害を起こさせた。得られた病変の組織像は，眼杯内板のロゼット形成および配列異常よりなるfoldingと，内板の外反による色素上皮層および脈絡膜血管の欠損であり，成熟ラットに観察された組織像と一致する所が多かった。

したがって，胎生期の眼杯裂閉鎖障害により視神経の分化が一部障害され，retinal dysplasia, coloboma, retinocele等の眼病変がもたらされるものと考察した。

ビーグルの視覚器の発達を出生直後から経時的に6カ月間にわたり，肉眼観察および電気生理学的手法により検索した。眼瞼開裂は生後9～12日齢にみられた。視覚誘発電位(VEP)では，12日齢から陰性波を記録した。一方，網膜電位(ERG)では，16～19日齢でa波が現れ，b波はやや遅れて18～22日齢で出現した。また，律動様小波は23～25日齢で発生したが，各波(O₁, O₂, O₃, O₄)が明瞭となるのは6週齢を過ぎてであった。aおよびb波の潜時時間は4週齢以降はほぼ安定し，6カ月齢まで殆ど同様であった。なお，眼圧測定では17日齢から25mmHg前後の値を示し，成犬のそれとほとんど変わらず6カ月齢まで安定した値を示した。

ERGおよびVEP検査時の光刺激に基づくと思われる眼底出血が観察された。網膜出血は19例中4例に発現し，1例では両側性，残り3例では片側性であった。また，出血部位はいずれも乳頭横鼻側であり，出血発生日は21～26日に集中した。出血は一過性のものであり，早いものでは6日，遅いものでは50日で出血跡は消失した。

その他，ERG検査後に角膜混濁および血管新生が1例で認められた。

Introduction: It has been shown that zinc pyrithione (Z-PT) causes retinal lesions in animals having a tapetum. We studied these lesions ophthalmoscopically, electroretinographically and histopathologically.

Young beagles were given orally a synthesized chymotrypsin inhibitor (FK-401) at doses of 100, 300, and 600 mg/kg/day for 35 days. Ophthalmoscopic observation revealed discoloration of the tapetum lucidum in one out of six dogs given 300 mg/kg, and in four out of eight dogs given 600 mg/kg. No changes were observed in the electroretinogram. Swelling of tapetal cells and vacuolation of arteriolae were observed in light microscopy, and enlargement of the tapetal rods was observed in electron microscopy. The tapetal discoloration induced by FK-401 at 600 mg/kg was irreversible during the 8-week recovery period. We concluded that the mechanism of tapetal discoloration was different from that produced by a zinc chelator or by beta-adrenergic blocking agents. The tapetum lucidum discoloration might be related to vacuolation of the tapetal cells. Our results suggest that retinal function could be disordered by longterm administration of FK-401. However, tapetal change was considered to be of no significance in species that do not have a tapetum lucidum.