tailieunhanh - Fundamentals of Clinical Ophthalmology (part 3)

Kể từ khi độ mở ống kính mi không chỉ bị ảnh hưởng bởi mức độ của ptosis mà còn bởi vị trí nắp thấp hơn (Hình ), nó là đôi khi hữu ích hơn để có được những bệnh nhân fixate một nguồn sáng điểm ở vị trí chính và để đo khoảng cách từ ánh sáng giác mạc | 5 Ptosis Ruth Manners Blepharoptosis describes a drooping of the upper eyelid and is derived from the Greek words blepharon eyelid and ptosis falling down. The term is almost invariably abbreviated to ptosis. Assessment of ptosis There are many features both ophthalmic and systemic which need to be assessed to elucidate the cause of ptosis and plan management History The history should include the following information age of onset family history past ocular history including previous intraocular or lid surgery predisposing factors such as contact lens wear or trauma episodes of lid swelling whether the ptosis worsens throughout the day the presence of any aberrant lid movements whether eye movements are impaired and if there is diplopia. The past medical history and current medications are also important when planning surgery. Palpebral aperture PA With the eyes in primary position the widest distance between the upper and lower lid margins is measured in millimetres with a transparent ruler held directly in front of the lids Fig. . It is important to ensure there is no 32 frontalis overaction. Drawings and photographs are often the easiest method of describing contour abnormalities scleral show etc. Margin-reflex distance MRD Since palpebral aperture is not only affected by the degree of ptosis but also by the lower lid position Figure it is sometimes more useful to get the patient to fixate a point light source in the primary position and to measure the distance from the corneal light 9 PA 9 5 5 Figure Palpebral aperture measurement. a Vertical measurement. b Same vertical measurement with left ptosis compensated by left lower lid retraction. c Margin reflex distance measurement. PTOSIS reflex to the upper lid margin MRD1 and from the reflex to the lower lid margin MRD2 Figure . The two numbers are recorded thus 4 MRD 1 3 5 MRD 2 5 The upper lid may obscure the visual axis in which case MRD 1 is recorded as a negative number. Accentuation In .