3/4/2024 0 Comments Eye shape names![]() ![]() Pretarsal segment of the Orbicularis Oculi Muscle The orbital segment provides voluntary forced closure of the eyelids. Orbital Segment of the Orbicularis Oculi Muscle Palpebral segment: further subdivided into the pretarsal and preseptal segments There are 2 sections of the orbicularis oculi muscle: When considering certain treatments for conditions such as ectropion or entropion, this may potentially help understand why and how to repair the eyelid tissues. In this framework, the orbital septum separates the anterior tissues from the posterior tissues. Anterior and Posterior LamellaeĪnother method of thinking about eyelids (especially in surgery) is dividing the eyelid into anterior and posterior lamellae. This will be discussed in a separate section. The eyelid margin is another unique aspect of the eyelids, which is important to understand for surgical landmarks and various pathologies. Müller muscle (inferior tarsal muscle in the lower eyelid) Levator palpebrae superioris muscle (not present in the lower eyelid) Subcutaneous connective tissue (the Oculoplastics BCSC book lumps the skin and subcutaneous tissue into one layer, as clinically they are fairly indistinct) After all, if you are doing eyelid surgery, you are going to make an incision through various layers of the eyelid and it’s helpful to know what tissues you’re cutting through and in what order. I personally have found that thinking through the layers of the eyelid from anterior (external) to posterior (internal) makes the most sense to me. The Fundamentals BCSC book lists 9 structures, while the Oculoplastics BCSC book lists 7 structures they are essentially the same lists so there’s no need to fret over which list to memorize. There are several ways to mentally organize the multiple layers of the upper eyelid. ![]() Levator Palpebrae Superioris Function (Excursion) ![]() MRD1 + MRD2 should equal the palpebral fissure height. MRD2: lower eyelid margin-to-light reflex MRD1: upper eyelid margin-to-light reflex this is probably the single most important measurement when evaluating ptosis. There are two margin-to-reflex distances ( MRD), corresponding to the measurement from the upper and lower eyelids: It is measured by having the patient fixate on a light, and measuring the distance from the margin of the eyelid to the corneal light reflex. This is a key measurement that you need when assessing for ptosis.Īs you might expect, it is the distance from the eyelid margin to the corneal light reflex. The normal palpebral fissure height is 8-11 mm. The palpebral fissure vertical height ( PFH) is measured between the margin of the lower eyelid to the margin of the upper eyelid. The palpebral fissure refers to the normal exposed area between upper and lower eyelids. ![]()
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