The orbit is a bony cavity in the upper half of the skull, shaped like a pyramid. It contains the eyeball (or globe), which is the organ of vision. Various accessory ocular structures, including the extraocular muscles which move the eye, and associated nerves and ligaments are present in this cavity.

The visible eye is about one-sixth of the entire eyeball, with three interacting components: the white sclera, the coloured iris and the black pupil.

1. The white colour of the exposed sclera is important as it contrasts with the darker iris and pupil.
2. The layperson term ‘eye colour’ refers to iris pigmentation, which is genetically determined. The iris is named after the rainbow, though its range of colour extends only from light blue to very dark brown. 
3. The pupil is the opening within the iris through which light passes to the inner aspects of the eye.

The eyelids (palpebrae) are two thin moveable folds that cover the anterior surface of the eye. By their closure, they function to protect the eye from trauma or excessive light. 

The medial commissure where the upper and lower lids meet is the medial canthus; laterally it is the lateral canthus. The actual palpebral fissure encompasses the exposed area between the top and bottom eyelids. The adult palpebral fissure is typically about 3 cm horizontally and 0.8 to 1.1 cm vertically. The upper eyelid margin overlaps the superior iris limbus (circular areas of pigment around the iris) by 1 – 2 mm. There should be minimal or no scleral exposure between the lower lid margin and the inferior limbus. The upper lid crease normally divides the upper lid into an inferior tarsal portion (lower one-third) and a superior septal portion (upper two-thirds).

The skin overlying the eyelids is thin and densely adherent to the margins of the palpebral fissure, eyelashes are the short hairs that grow along the edge of our eyelids and protect our eyes from dust.

The eyebrows (Latin: supercilia) are situated at the junction of the forehead and the upper eyelid. The female eyebrow is positioned above the supraorbital rim and is shaped like a gentle arc. The anatomy of the eyebrow consists of a medial and lateral end, with the lateral brow positioned up to 10 mm superior to the supraorbital rim; the medial brow is usually 2 mm inferior to the lateral brow. Typically, in women, the highest point or peak of the eyebrow arc/arch should be level with the lateral canthus but may be anywhere between the lateral limbus and lateral canthus of the eye. The lateral most of the female eyebrow is on a line tangent to the lateral canthus from the nasal ala.

Typically women have larger eyes due to wider eye sockets and larger palpebral openings. Larger eyes are both a neotenous feature and an indicator of high levels of oestrogen.

Almond shape eyes with high angularity are a western norm and eastern standards prefer a rounder less angular eye shape.

Research by Pamela M. Pallett et al shows that when the face’s eye-to-mouth distance is 36% of the face length and interocular distance is 46% of the face width, the face reaches its optimal attractiveness given its unique facial features. 

Ideal proportional relationships of the orbital region to the rest of the face are described as the rule of fifths. According to that, the ‘ideal’ face may be transversely divided into five equal parts, each roughly equal to one eye width.

There should be minimal or no scleral exposure between the lower lid margin and the inferior limbus; excessive scleral exposure below the iris is a sign of midfacial hypoplasia.

The mean tilt for 

1. Attractive Korean face is +8.87
2. Attractive Asian face is  +8.64
3. Attractive Caucasian face is +7.13
4. Attractive African face is +9.98

Marked fissure obliquity is found more frequently among Africans, Korean and Asians than among Caucasians.

Accentuated medial canthal tilt is considered highly attractive. The fact that palpebral fissure inclination is steeper in children than in adults makes it a neonatal feature. It is also interesting to note that it is again steeper in females than males after puberty making it a sexually dimorphic feature.

The reason for this is when the inner corner is lowered, the canthal tilt is higher and positively associated with increased femininity and attractiveness.

The medial curvature of the eyebrow continues with a smooth transition onto the aesthetic dorsal line of the nose; this curvilinear relationship is termed the brow – nasal tip aesthetic line. In men, the brow – nasal tip aesthetic line is more angular, in the form of an inverted ‘ L ’ whereas in women it distinctly curves at the junction of the nose and the eyebrow.

It should be well defined and essentially parallel to the upper lid margin and should not extend beyond the medial and lateral canthi. It normally divides the upper lid into an inferior tarsal portion (lower one-third) and a superior septal portion (upper two-thirds). This may be absent in Far Eastern patients, and ageing may become concealed behind redundant, ptotic skin (dermatochalasis).  A useful guideline is to maintain a distance of approximately 15 mm between the eyebrow and the upper lid crease when planning a monolid surgery. The normal range of the distance from the central upper lid margin to the lid crease in white Caucasians should be 7 – 10 mm.

Mild left-right asymmetry in the orbital and periorbital region is relatively common, but the presence of marked asymmetry in this region is very noticeable. Clinical evaluation of orbital and periorbital symmetry should be undertaken with the patient in repose and in animation, i.e. varying gaze and raising/lowering the eyebrows.