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Intracorneal Ring Segments⁣




● Two tiny clear crescent-shaped pieces of PMMA 150 degree inserted into the⁣

cornea⁣

● Placed in mid-corneal peripheral stroma at approximately 2⁄3 depth outside⁣

central optical zone to reshape anterior corneal surface while maintaining⁣

prolate profile (positive asphericity) of cornea⁣

● Act as spacer elements between the bundles of corneal lamellae producing a⁣

shortening of the central arc length (arc shortening effect) that is proportional to⁣

thickness of device⁣

● Central portion of anterior corneal surface tends to flatten and peripheral⁣

area adjacent to ring insertion is displaced forward ⁣

Most common type of ICRS : ​INTACS⁣

Hexagonal transverse shape - 8.1 mm external & 6.8 mm internal diameter ⁣

Refractive effect is modulated by thickness (0.25-0.45 mm, with 0.05-mm increments)- current designs have a predicted myopic range of correction from -1.00 to -4.10 D⁣

Incision made with femtosecond laser or mechanically with a diamond knife and a tunnel created by a dissector into which the ring segments are placed⁣

Other types: Ferrara rings, KeraRing, MyoRing, Bisantis Segments⁣

Requirements: Age >21 years⁣

Clear, central cornea⁣

Minimum corneal thickness of 450 microns at incision site⁣

Mesopic pupil size of less than 6 mm⁣

Indications:⁣

Low myopia⁣

Progressive keratoconus⁣

Ectasia after LASIK⁣

Residual myopia after LASIK⁣

Pellucid marginal degeneration⁣

Contraindications:⁣

● Keratoconus patients who can achieve functional vision on a daily basis using contact lenses⁣

● Age <21 y⁣

● Dont have clear central corneas⁣

● Corneal thickness < 450 μ at proposed incision site⁣

● Patients with collagen vascular/autoimmune diseases⁣

● Ocular conditions - recurrent corneal erosions, corneal dystrophy⁣

● Systemic diseases which affect wound healing -diabetes⁣

Advantages:⁣

● Leaves central cornea undisturbed⁣

● Rapid results, predictable⁣

● Reversible⁣

● Corneal asphericity is maintained with minimal adverse effects⁣

Complications:⁣

● Epithelial defects⁣

● Channel haze⁣

● Under/ Over-corrections⁣

● Sterile infiltrates/ epithelial cysts⁣

● Ring extrusion⁣

● Cornea thinning ⁣

● Infectious keratitis


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Image from Rajan Eye Care Hospital #ophthalmology #ophthal #doctor #health #medical #vision #education #optometry #medicalstudent #optometrist #medicine #eye #ophtho #ophthalmologist #ophthalmo #med #medicaleducation #ophthalmologyresident #ophthalmologyresidency

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Congenital Ptosis⁣


⁣AD⁣, Myogenic dysgenesis of the LPS -fibrous & adipose tissue in muscle belly⁣

Impairs ability of muscle to contract and elevate lids⁣

May occlude pupil - amblyopia⁣

Compression of eyeball by ptotic lid⁣ - astigmatism⁣

Severe bilateral congenital ptosis - compensatory head posture- chin up position - to obtain good vision ⁣




Simple congenital ptosis⁣

Due to dystrophy of LPS⁣

Increases in upgaze⁣

Lid lag in downgaze as muscle does not relax⁣

normally⁣

Lid crease absent ⁣

LPS action <4mm⁣

Synkinetic ptosis⁣

Aberrant innervation of LPS muscle by mandibular branch of 5th⁣ nerve ⁣

Marcus-Gunn jaw winking⁣

Brisk upper lid retraction- mastication, jaw thrusting to opp side, chewing,⁣

smiling, jaw protrusion or sucking due to ipsilateral pterygoid muscle contraction⁣

Infants while bottle/breast-fed⁣

Aponeurotic ptosis⁣

Aponeurosis fails to insert on anterior surface of the tarsus/from birth trauma⁣

following forceps delivery⁣

Skin crease may remain normal or high without lid lag on down gaze, good LPS⁣

function⁣

Blepharophimosis syndrome⁣- AD⁣

Blepharophimosis,telecanthus,epicanthus inversus,ptosis⁣

⁣Ovarian failure,arched palate,cardiac defects⁣

Neurogenic ptosis⁣

Ptosis,miosis,anhidrosis and progressive heterochromia - Horner’s⁣ Syndrome⁣

Rule out:congenital varicella,vascular lesions of internal carotids/subclavian⁣

artery & tumors of neck and mediastinum⁣

Congenital third nerve palsy⁣

Partial/complete⁣

Ptosis, inability to elevate, depress or adduct eye, dilated pupil⁣

Pupil - paradoxically small & non-reactive - sign of aberrant regeneration⁣

Others⁣: Birth trauma, Duane syndrome, CFEOM, Kearns Sayre syndrome, Myotonic dystrophy, Myasthenia⁣

Surgical Indications⁣: Stimulus deprivation/induces astigmatism that is amblyogenic⁣, Cosmesis⁣

Surgeries⁣

Frontalis Sling-< 3-4 years of age with poor LPS function⁣

Levator resection & advancement - LPS function >5mm⁣

LPS <3mm - frontalis suspension, frontalis muscle flap, Whitnall's ligament suspension⁣

Whitnall sling (with/without tarsectomy) - cases of relapse after⁣ frontalis suspension and vice versa⁣

Fasanella-Servat⁣

Muller’s muscle conjunctival resection



Image from Rajan Eye Care Hospital


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