Ophthalmics: Definition, Dosage Forms & Aseptic Filling
Last updated: 19 November 2025
Ophthalmics are sterile medicinal products used for therapeutic and diagnostic purposes, applied directly to the eye. This includes eye drops, suspensions, emulsions, gels, ointments, ocular inserts, and intra- or periocular injections (e.g. intravitreal or intracameral injections). Sterility is critical for all ophthalmic products to maintain efficacy and prevent microbial contamination and infection.
What are the areas of application for ophthalmic products?
The field of application for ophthalmic drugs encompasses numerous eye diseases, which in turn influence the appropriate dosage form and the type of active ingredients.
The following classes of active substances are distinguished:
- Local anesthetics
- Diagnostic dyes
- (Pupil-constricting) miotics
- (Pupil-dilating) mydriatics
- Antiallergics
- Antiphlogistics
- Anti-infectives
- Tear replacement fluid
Common dosage forms of ophthalmics
The classic and most common dosage form of ophthalmics is eye drops, typically formulated as aqueous or oily solutions, suspensions, or emulsions. In addition, the following ophthalmic dosage forms are used:
- Eye baths and irrigating solutions
- Eye sprays (e.g. liposomal sprays applied to the closed eyelid margin)
- Powders for reconstituting eye baths and drops
- Ocular inserts (solid, drug-releasing devices)
- Semi-solid ophthalmic preparations such as eye ointments and gels
In addition, ophthalmic injections (e.g. intravitreal, intracameral, subconjunctival, or sub-Tenon injections) are parenteral ophthalmic dosage forms that are administered in or around the eye.
The administration of ophthalmics takes place by application to the eyeball, into the conjunctival sac, or by intra-/periocular injection. Besides compatibility and stability, sterility of the product is crucial to ensure reliable efficacy and to avoid complications due to contamination. Ophthalmics are therefore highly sensitive products with strict requirements regarding sterile filling.
How are ophthalmics manufactured?
In the manufacture of an ophthalmic product, several formulation goals are in focus, such as achieving higher ocular bioavailability with the lowest possible dose and dosing frequency. One common strategy is to improve wetting and residence time on the ocular surface by increasing the viscosity of the formulation using oily carriers or hydrophilic polymers (e.g. cellulose derivatives). For aqueous eye drops, target viscosities of approximately 15–25 mPa·s (in some cases up to about 30 mPa·s) are widely used to prolong residence time in the eye without compromising drop formation or visual acuity.
Because ophthalmics come into direct contact with highly sensitive ocular tissues, sterility is mandatory. In multi-dose containers, preservatives are traditionally added to prevent contamination after opening. Typical examples still in use are quaternary ammonium compounds such as benzalkonium chloride (BAC), whereas older preservatives like thiomersal are now rarely used due to safety concerns. Today, preservative-free (PF) multi-dose ophthalmics are increasingly preferred. They rely on specialised container and closure systems (e.g. COMOD® or Novelia® multi-dose systems) that use one-way valves and microbiological barriers to keep the formulation sterile over its in-use shelf life without the need for antimicrobial preservatives.
Aseptic filling of ophthalmics
The aseptic nature of ophthalmics can generally be ensured in two ways:
- Terminal sterilisation in the final container, where the product is sufficiently stable to withstand the sterilisation process (e.g. moist heat).
- Aseptic processing, including sterile filtration (≤ 0.22 µm) with validated filter integrity testing, followed by filling into pre-sterilised containers under Grade A conditions with an appropriate background classification.
BFS Technology: Blow-Fill-Seal for ophthalmics
In the aseptic filling of ophthalmics, modern Blow-Fill-Seal (BFS) systems have proven to be efficient and reliable solutions. The production of sterile polymer containers, their filling with the ophthalmic drug and their sealing take place in one fully automated, integrated process (Blow – Fill – Seal).
In BFS technology, polymer granules are first extruded into a hollow tube (parison). The parison is enclosed by a mould and formed into the final container using vacuum and sterile air. Immediately afterwards, the exact dose of the ophthalmic solution is filled into the container and the container is hermetically sealed – all within a closed system and without manual intervention. Depending on the system type, up to around 33,000 units per hour can be produced, with typical fill volumes from about 0.1 to 50 ml for ophthalmic ampoules.
Advantages of Blow-Fill-Seal for ophthalmic drugs
- Minimised contamination risk due to a closed, highly automated filling process
- Easy opening, dosing and application for the user
- Reduced logistics and handling costs
- Flexible container design with high impact resistance
- Use of recyclable polymers (e.g. PE, PP)
- Production of single-dose and multi-dose ophthalmics, including preservative-free formats
- BFS lines can be designed to comply with GMP regulations and EU Guideline Annex 1 for aseptic manufacturing