Ophthalmic surgical agents

Definition and Scope

Ophthalmic surgical agents are a pharmacological class of sterile, specialized preparations used during ocular surgeries to support, protect, or manipulate the ocular environment. These agents are integral to cataract surgery, vitreoretinal procedures, corneal transplantation, glaucoma filtering surgeries, and refractive interventions. They do not possess intrinsic therapeutic effects (like anti-infective or anti-inflammatory agents) but play mechanical, lubricating, viscoelastic, osmotic, or protective roles. Their use enhances surgical precision, improves outcomes, and preserves ocular integrity during and after operative interventions.

This pharmacological class includes:

• Viscoelastic substances (OVDs)

• Irrigating and intraocular solutions

• Dyes and stains

• Mydriatics for surgical dilation

• Ophthalmic hemostatic agents

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1. Mechanism of Action and Subtypes

a. Viscoelastic Devices (OVDs)

• Maintain anterior chamber depth

• Coat and protect corneal endothelium

• Facilitate lens implantation

• Displace or tamponade tissues intraoperatively

• Mechanism: Physical cushioning, lubrication, space maintenance

b. Irrigating Solutions

• Maintain corneal hydration

• Flush out debris or viscoelastic remnants

• Preserve ocular tissue pH, osmolarity, and ionic balance

• Mechanism: Sterile isotonic irrigation with balanced electrolytes

c. Vital Dyes

• Stain ocular tissues to enhance visualization

• Used in capsulorhexis, vitreoretinal surgery

• Mechanism: Tissue-specific affinity and selective uptake

d. Mydriatics/Intraoperative Pupil Management

• Facilitate lens extraction and implantation

• Maintain dilated pupil intraoperatively

• Mechanism: Alpha-adrenergic receptor agonism and/or muscarinic antagonism

e. Hemostatic Agents (less common in ophthalmology)

• Control minor intraocular bleeding

• Mechanism: Topical coagulants or vasoconstrictors

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2. Representative Agents

Category	Generic Name	Brand Examples
Viscoelastics (OVDs)	Sodium hyaluronate	Healon, Provisc, Amvisc
	Hydroxypropyl methylcellulose (HPMC)	OcuCoat
	Chondroitin sulfate + sodium hyaluronate	Viscoat
	2% HPMC	Aprovisc
Irrigation Solutions	Balanced Salt Solution (BSS)	BSS, BSS Plus
	Lactated Ringer’s solution	–
	Phosphate-buffered saline	–
Dyes (Intraocular)	Trypan blue	VisionBlue, Blulife
	Indocyanine green	IC-Green
	Brilliant blue G	ILM Blue, Brilliant Peel
	Fluorescein sodium	Fluorescite (for intra-op staining)
Mydriatics (intra-op)	Phenylephrine	Mydfrin, Omidria (w/ ketorolac)
	Tropicamide	Mydriacyl
	Cyclopentolate	Cyclogyl
	Atropine sulfate	Atropisol
Combination agents	Phenylephrine + ketorolac	Omidria
Other surgical adjuncts	Perfluorocarbon liquids (PFCLs)	Perfluoron
	Silicone oils	Siluron, Oxane
	Air/gas tamponades	SF6, C3F8

3. Therapeutic and Surgical Applications

Surgical Setting	Function of Agents Used
Cataract surgery	Maintain anterior chamber (OVDs), stain capsule (trypan blue), maintain mydriasis
Vitreoretinal surgery	ILM or ERM peeling (vital dyes), retinal tamponade (gases/silicone oil), endo-illumination
Corneal surgery	Stromal dissection (OVDs), endothelial cell protection
Glaucoma filtration surgery	Intra-op viscoelastic to maintain chamber; sometimes dye use
Refractive surgery	Irrigation and debris removal

4. Mechanism-Specific Details

a. Sodium Hyaluronate

• A naturally occurring glycosaminoglycan

• High molecular weight = cohesive OVD

• Used to maintain space, facilitate IOL implantation

• Removed easily at end of surgery

b. Hydroxypropyl Methylcellulose (HPMC)

• Dispersive OVD

• Better for coating and protecting endothelium

• Harder to remove, longer tissue contact

c. Balanced Salt Solution Plus (BSS Plus)

• Contains additional glucose, bicarbonate, glutathione

• Mimics aqueous humor composition

• Preserves cellular function intraoperatively

d. Trypan Blue

• Selectively stains anterior lens capsule

• Improves visualization during capsulorhexis in white cataracts

e. Brilliant Blue G

• Stains internal limiting membrane (ILM) in retinal surgery

• Minimizes phototoxicity vs indocyanine green

f. Phenylephrine + Ketorolac (Omidria)

• Phenylephrine: alpha-1 agonist, sustains pupil dilation

• Ketorolac: NSAID, reduces intraoperative miosis and pain

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5. Dosage Forms and Routes

Form	Route	Examples
Solution (viscoelastic)	Intraocular injection	Healon, Viscoat
Solution (irrigation)	Continuous infusion	BSS, BSS Plus
Dye solution	Intracameral/intravitreal	Trypan blue, Brilliant blue
Mydriatic solution	Topical/intracameral	Tropicamide, Omidria
Gas/liquid tamponade	Intravitreous injection	SF6, Silicone oil

All products must be sterile, preservative-free, and pH/osmolality-balanced for intraocular use.

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6. Adverse Effects

While these agents are relatively safe under surgical conditions, some may cause:

Agent Class	Possible Adverse Effects
Viscoelastics (OVDs)	↑ Intraocular pressure (IOP) if not removed properly
Irrigating solutions	Corneal edema, endothelial damage if improperly balanced
Vital dyes	Retinal toxicity (e.g., indocyanine green), inflammation
Mydriatics	Tachycardia, hypertension (systemic absorption of phenylephrine)
Silicone oils	Cataract formation, emulsification, glaucoma
Gas tamponades	↑ IOP, contraindicated with air travel

7. Contraindications

Agent Type	Contraindications
Phenylephrine-based agents	Uncontrolled hypertension, narrow-angle glaucoma
Indocyanine green	Iodine allergy
Gas tamponades	Need for early air travel, severe glaucoma
High-viscosity OVDs	Narrow-angle glaucoma (if not fully removed post-op)

8. Precautions and Monitoring

Area	Monitoring Recommendations
Intraocular pressure	Post-op IOP checks if viscoelastic not fully aspirated
Endothelial health	Use dispersive agents in compromised corneas
Pupil size	Ensure adequate dilation during intraoperative procedures
Retinal safety	Limit dye concentration and exposure duration
Systemic effects	Monitor BP/HR with phenylephrine

9. Drug Interactions

Generally minimal, due to localized intraoperative use. However:

• Phenylephrine may interact with MAO inhibitors, tricyclic antidepressants, and beta-blockers

• Indocyanine green may cause anaphylaxis in patients allergic to iodinated contrast agents

• Ketorolac can increase bleeding risk when combined with anticoagulants

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10. Storage and Handling

Agent	Storage Requirements
Viscoelastics	Refrigerated or room temperature, avoid light exposure
Irrigation solutions	Use immediately once opened, sterile technique essential
Dyes	Protect from light; discard unused portion
Silicone oils/gases	Temperature-stable, handled under aseptic conditions

All agents are for single-use only and must be preservative-free for intraocular safety.

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11. Special Populations

Population	Consideration
Pediatric patients	Ensure age-appropriate dosing and agents
Elderly patients	↑ sensitivity to mydriatics and IOP fluctuation
Glaucoma patients	Monitor IOP closely post-op with OVDs, tamponades
Iodine-allergic patients	Avoid indocyanine green

12. Regulatory and Clinical Practice Guidelines

• All intraocular agents are regulated as sterile surgical products under FDA, EMA, and local agencies

• Clinical guidelines provided by:

  • American Academy of Ophthalmology (AAO)

  • European Society of Cataract and Refractive Surgeons (ESCRS)

  • Royal College of Ophthalmologists (UK)

These guidelines endorse the use of dispersive and cohesive OVDs in sequence, recommend dye concentration limits, and stress proper removal of agents to avoid complications.

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13. Summary Table of Common Ophthalmic Surgical Agents

Agent Type	Example	Primary Use
Cohesive OVD	Healon	Maintain chamber space
Dispersive OVD	Viscoat	Coat endothelium
Irrigation Solution	BSS Plus	Maintain ocular hydration
Intraocular Dye	Trypan Blue	Capsule staining
Mydriatic Combo	Omidria (phenylephrine + ketorolac)	Maintain pupil & reduce pain
Gas Tamponade	SF6, C3F8	Retinal reattachment
Silicone Oil	Siluron	Long-term tamponade