eyelid reconstruction lower eyelid

eyelids have been identified:

single eyelid: no lid crease with puffiness

low eyelid crease: low-seated, nasally tapered, inside-fold type of crease

double eyelid: lid crease parallel to the lid margin Jeong et al found that there are three reasons for the absent or lower crease in the Asian upper eyelid:

The orbital septum fuses to the levator aponeurosis at variable distances below the superior tarsal border.

Preaponeurotic fat pad protrusion and a thick subcutaneous fat layer prevent levator fibers from extending toward the skin near the superior tarsal border.

The primary insertion of the levator aponeurosis into the orbicularis muscle and into the upper eyelid skin occurs closer to the eyelid margin in Asians.

The lower eyelid crease is formed by the fascial extensions of the capsulopalpebral fascia, which also pass through the orbicularis oculi muscle and insert onto the skin.Lim et al. reported that in Asians, these fascial extensions do not extend to the skin; therefore, a palpebral crease is not found. Kakizaki et al.
stated that the reason for the indistinct lower lid crease in Asians is the higher or indistinct septum fusion, the anterior and superior orbital fat projection, and the overriding of the preseptal orbicularis muscle.

Eyelid Margin and Lacrimal Pump

The eyelid margin has several significant structures. Both the upper and lower eyelid margins have a punctum medially. The punctum opens into the canaliculus of the lacrimal system. Tears drain via the canaliculi and into the nasolacrimal sac and then to the lacrimal duct by both an active and a passive mechanism. The lacrimal pump actively sucks tears into the lacrimal sac with each blink. The contraction of the orbicularis muscle brings the lower punctum medially, closes the ampulla, and displaces the lateral wall of the lacrimal sac laterally, creating a negative pressure in the sac.

lower eyelid

Thursday, February 21, 2013