The abovementioned ablative processes of cryotherapy have been used in various surgical disciplines. These included dermatological, oral and maxillofacial, general and gynecological surgery [10,11,12]. Especially in recent years, the field of cryosurgery received a new wave of interest in the treatment of prostate cancer and breast cancer [13, 14].

Cryosurgery in surgical procedures of the orbit

Ablative cryosurgery was also used extensively in ophthalmological surgery starting as early as the 1930s with the treatment of retinal tears [10]. To date, cryoablation in ophthalmological surgery remains in use for a variety of different conditions such as glaucoma, cataract, retinopathy, disorders of the eyelid or neoplastic lesion [22,23,24,25,26].

Additionally, the adhesive effect of a cryoprobe came into the focus of interest after the first description of its use for removal of orbital masses [1, 9]. As a result, it became clear that certain advantages exist for both the ablative effect as well as the adhesive effect of cryosurgery during surgery of orbital pathologies. For demonstration of the cryoadhesive effect for removal of a cavernous venous malformation in an illustrative case see video 1 (supplementary material).

Advantages and disadvantages of cryosurgery

An advantage of cryoablation is the direct visual control of the ablation progress. During cryoablation the lesion undergoes a phase transition forming an ice ball that is attached to the tip of the device. This allows the surgeon to dissect the tumor out of the surgical site very safely and clearly using gentle traction. This means that lesions that are otherwise difficult to grasp can be removed en bloc in a narrow and complex anatomical space due to the intraorbital fat tissue. Another theoretically potential advantage of cooling may be the anesthetic effect that is provided by cryoablation in comparison to resection by thermocoagulation [27].

Furthermore, the developing adhesion through the ice ball formation allows gentle manipulation of an orbital mass and removal with reduced risk of opening the lesion or tearing off a capsule [1, 2]. Moreover, the freezing effect of the tumor itself but also close vessels can lead to reduced bleeding during the removal [1].

Orbital pathologies suitable for removal with a cryoprobe

After initial case series, the application of the cryoadhesive effect for removal of orbital tumors gained remarkable interest with orbital surgeons [1, 7, 28]. Several studies reported the use of cryoprobes for the removal of different orbital tumors with variable success. The most suitable lesions represent well-circumscribed encapsulated masses with no relevant adhesions or tendency to infiltrate surrounding structures. Therefore, orbital cavernous venous malformations represent the most suitable lesions as they consist of dilated venous channels that are typically surrounded by a thin fragile capsule (video 1, supplementary material) [29, 30]. They are also the most common benign intraorbital mass, typically requiring resection only if they show growth on serial imaging or become symptomatic or lead to disfiguring proptosis [2, 29, 30].

Besides cavernous venous malformations schwannomas, hemangiopericytomas, dermoid or epidermoid cysts and meningiomas within the orbit are also well-circumscribed benign lesions in which the use of a cryoprobe can facilitate complete removal [1, 7, 9]. In addition, some cases of removal of malignant tumors with the use of a cryoprobe were also reported and include rhabdomyosarcoma or carcinomas [1, 7]. In these situations, removal with a cryoprobe can also facilitate en bloc resection without rupture of the lesions and spillage of malignant tumor cells [1, 7].

In pathologies that infiltrate surrounding tissue like the eyeball, muscles but also the surrounding bone, the application of cryosurgery is of limited value [1, 7]. This also applies to diffuse pathologies, although some authors advocate using cryosurgery also for tissue acquisition during biopsy procedures [1, 2, 7].

Possible approaches for cryoextraction of orbital masses

Traditionally, a lateral orbitotomy (Kroenlein approach) represented the workhorse for the extraction of orbital masses [5, 7, 9, 28]. This applied to both traditional procedures with grasping forceps or threads to resect orbital lesions as well as surgical procedures with the application of a cryoprobe [1, 3, 5, 7, 9]. Over the years, various transcranial approaches but also anterior transconjunctival approaches have been applied and advocated to remove orbital masses with cryoextraction [1,2,3, 7, 28, 31].

In recent years, the application of a cryoprobe for the removal of intraorbital masses was also used in endoscopic transnasal approaches leading to a small number of published cases reports [4, 6, 8, 32].